The invention discloses a double-thimble rotor shaft entry device, which comprises an upper thimble assembly, a lower thimble assembly arranged below the upper thimble assembly and coaxial with the upper thimble assembly, and a limiting assembly connected with the upper thimble assembly and the upper thimble assembly, and a pressure assembly is also connected with one or both of the upper thimble assembly and the limiting assembly. The utility model adopts the structure of upper and lower thimbles to fix the shaft in the vertical direction and directly press it into the rotor through linear force. By adopting the shaft feeding method and device, the shoulder on the shaft can be omitted, and there is no need to leave grinding allowance on the bearing seat, which not only saves the material cost, but also reduces the processing cost. In addition, the shaft is fixed and positioned well in the vertical direction when entering the shaft, and the runout of the bearing gear after entering the shaft can be guaranteed to be within 0.05mm, which fully meets the requirements of the automobile alternator and saves the step of grinding the bearing gear after entering the shaft. The whole fixture itself has simple structure and low cost.