The invention discloses a gear shift execution mechanism used for an AMT. The mechanism comprises a gear shift drive device, a gear shift shaft, a shifting fork body and a synchronizer. The shifting fork body is connected with the synchronizer, and gear shift operation is achieved through the synchronizer. The gear shift execution mechanism further comprises a buffer block and buffer springs. A U-shaped groove is formed in the top face of the shifting fork body, and bosses are arranged on two end faces. The shifting fork body is provided with a penetrating through hole along the axes of the bosses. The gear shift shaft penetrates into the penetrating through hole of the shifting fork body. The buffer block is located in the U-shaped groove of the shifting fork body and penetrates into thegear shift shaft. The top face of the buffer block is connected with the gear shift drive device. The buffer springs penetrate into the gear shift shaft and are located between the two side faces of the buffer block and the two end faces of the U-shaped groove of the shifting fork body. One end of each buffer spring is sleeved into the corresponding boss on the corresponding end face of the U-shaped groove of the shifting fork body. By means of the execution mechanism, the defects of a traditional transmission gear shift structure are overcome, impacts generated gear shift operation are effectively reduced, the gear shift performance of the transmission is optimized, comfort of gear shift operation is improved, and reliable and safe driving of automobiles is ensured.