The embodiment of the invention provides a method for realizing cell handover, a base station and a mobile communication system. The method comprises the following steps: when the moving speed of a mobile station is greater than a speed threshold, discrete effective data corresponding to different time points is screened in a measurement report from the mobile station; the approximate expression of a continuous function is constructed according to the effective data; the continuous function is calculated according to the approximate expression; and the time interval required for the mobile station to reach a handover zone from a current position is estimated according to the moving speed and the continuous function, the handover time point at which the mobile station starts cell handover is calculated according to the time interval and the handover delay, and cell handover is started when the mobile station reaches the handover time point. The mobile station is ensured to have enough time to timely start cell handover before entering the handover zone and to smoothly complete the handover process, the handover delay of the mobile station is reduced, and the success rate of handover by the mobile station under high-speed movement is improved.