There are many manufacturers over there. Take a good look and choose for yourself.
By the way, I'll give you this reference
1. Harbin Tiancheng Plastic Steel Door and Window Factory (No.71Timber East Street)
2. Acheng Beixin Plastic Steel Door and Window Factory (in front of CPPCC Residential Building in Yongtaiguang Community)
3. Acheng Huaxing aluminum doors and windows factory (boiler factory and the old courtyard of Hexing Construction Engineering Company)
4. Acheng Xinhe Aluminum Windows and Doors Factory (Pailu South Street)
5. Harbin Xu Yan Aluminum Windows and Doors Factory (No.28 Minsheng Street)
6. Heilongjiang Hong Xin Plastic Steel Doors and Windows Co., Ltd. (No.30 Yi Kuang Street)
7. Aide Aluminum Doors and Windows Factory, Daowai District, Harbin (No.Nanbadao Street 10- 12)
8. Longxing Aluminum Window Factory, Longquan Town, Bayan County (Longquan Town)
9. Haoyunlai Aluminum Doors and Windows Factory, Daowai District, Harbin (Ji Le Village, Songbei Town)
10. Harbin Jin Quan Plastic Steel Door and Window Factory (Anguo Street 168)
1 1. Harbin Xinyu Aluminum Plastic Steel Door and Window Factory (No.61Chongbu Village, Songpu Town)
12. wuchang city Tianchen Aluminum Plastic Steel Door and Window Factory (opposite to wuchang city Tobacco Second Station)
13. Harbin Dexin Plastic Steel Windows and Doors Factory (Xinxiang Village, Yushu Township)
14. Long Da Plastic Steel Door and Window Factory in Harbin Power Zone (Da 'nan 'gou, Chaochao)
15. Harbin Sheng Hui Plastic Steel Door and Window Factory (No.2 Gongnong Erdao Street 195)
16. Exquisite aluminum alloy plastic-steel doors and windows factory in Xiangfang District, Harbin (No.2, Building Anbu Community 105)
17. Heilongjiang Tongfa Plastic Steel Doors and Windows Co., Ltd. (No.327 Garden Street)
18. shangzhi city Huayu aluminum doors and windows factory (No.52, Yongshun Road, Yabuli Town).
19. Wuchang Plastic Steel Door and Window Factory (No.4 Yachen Street, Wuchang Town (former leather factory yard))
20. Songbei Plastic Steel Door and Window Factory in nangang district, Harbin (No.49 Quxian Street)
2 1. Harbin Zhengyang Plastic Steel Door and Window Factory (No.282 Gongnong Street)
22. Hongye Plastic Steel Door and Window Factory in Daoli District, Harbin (Xiaobeitun, Nong Xin Town)
23. The first branch of Harbin Guo Hong Plastic Steel Door and Window Co., Ltd. (No.37 Daokoudao Street)
24. Harbin Kaiyada Plastic Steel Door and Window Factory (No.9 Xuefu Erdao Street)
25. Tian Yun Plastic Steel Door and Window Factory, nangang district, Harbin (Haxi Street 1No.)
26. Harbin Zhenhua Plastic Steel Door and Window Factory (No.40 Staff Street)
27. Harbin Xu Yang Plastic Steel Doors and Windows Co., Ltd. (Building 2 of Jixing Commercial and Residential City 1 Floor 30 Garage)
28. Heilongjiang Huajie Plastic Steel Doors and Windows Co., Ltd. (No.402 Xuefu Road)
29. wuchang city Meijia Plastic Steel Doors and Windows Co., Ltd. (diagonally opposite to No.3 Middle School of Aachen South Road)
30. Jinshi Plastic Steel Door and Window Factory in Xiangfang District, Harbin (Gongbin Road 1 14)
3 1. Xinfeng Aluminum Window Factory, Daowai District, Harbin (Qianjin Village, Songbei Town)
32. Changhua Aluminum Windows and Doors Factory, Taiping District, Harbin (No.76 Cement Road)
33. Xiangdian Aluminum Doors and Windows Factory in Xiangfang District, Harbin (Gongbin Road 142-2)
34. Acheng Longquan Aluminum Windows and Doors Factory (Xicheng District)
35. Hongda Plastic Steel Door and Window Factory, Daowai District, Harbin (Ji Le Village, Songbei Town)
36 Harbin Jialong Plastic Steel Doors and Windows Co., Ltd. (No.6 Bianxing Road)
37. Harbin Qingxin Plastic Steel Door and Window Factory (Dengjia Village, Liming Town)
38. wuchang city Shangshang Aluminum Plastic Steel Door and Window Factory (opposite to Tobacco Second Station)
39. Bayan Xinglong Feida Aluminum Windows and Doors Factory (Yude Street, Xinglong Town)
40. Guangming Plastic Steel Door and Window Factory in Harbin Power Zone (Danangou Village, Chaoyang Town)
4 1. Harbin Jiaxing Aluminum Window Factory (No.63-4 Shuiyuan Road)
42. Harbin Lirong Plastic Steel Door and Window Factory (No.37 Gongbin Road)
43. Xin Ming Aluminum Door and Window Factory in Daowai District, Harbin (Miaotaizitun, Liming Village, Songpu Town)
44. Langen Aluminum Windows and Doors Factory, Taiping District, Harbin (No.70-15, Beisandao Street)
45. Harbin Xintai Plastic Steel Door and Window Factory (Xin Ying Street 1No.)
46. Harbin Lvye Plastic Steel Door and Window Factory (Jinshan Village, Liqun Township)
47. Lan Xiang Plastic Steel Door and Window Factory, Daowai District, Harbin (Qianjin Village, Songbei Town)
48. Tianlongyuan Plastic Steel Door and Window Factory, Taiping District, Harbin (No.2 Woodland Street)
49. Deping Aluminum Doors and Windows Factory, Daowai District, Harbin (Xinzhen Village, Songbei Town)
50. nangang district Juxin Aluminum Plastic Steel Door and Window Factory (No.42 Haicheng Street) in Harbin.