You can't. According to Article 36 of Hangzhou City Appearance and Environmental Sanitation Management Measures, it is forbidden to release or throw balloons, firecrackers, fireworks and other items that are likely to cause danger, pollute the environment and disturb social order in public places. As a famous scenic spot in Hangzhou and a public place, the West Lake is not allowed to fly balloons. In addition, we should pay attention to environmental protection. Flying balloons is easy to cause environmental pollution and eating by animals. It is not recommended to fly balloons anywhere.