The utility model discloses a middle transmission box of a personnel air lock. The middle transmission box of the personnel air lock comprises a box body. The box body is composed of a left box body, a right box body and a middle box body. A bevel gear set and a hand wheel are installed inside the left box body. A bevel gear set and a hand wheel are installed inside the right box body. A motor and a speed reducer are installed inside the middle box body. The box body is connected with a cylinder body of the personnel air lock through bolts. A left output shaft and a right output shaft are arranged on the speed reducer. The left output shaft and the right output shaft are in the same plane, and are arranged in a front-and-back mode. The right output shaft is connected with a transmission shaft IV through a right side electromagnetic clutch, the right output shaft is in linkage with a transmission shaft I through a right side chain wheel device, and the transmission shaft I is supported inside the left box body. The left output shaft of the speed reducer is connected with a transmission shaft II through a left side electromagnetic clutch, the left output shaft is in linkage with a transmission shaft III through a left side chain wheel device, and the transmission shaft III is supported inside the right box body. A bevel gear set is installed on the transmission shaft I or the transmission shaft III, and the bevel gear set is connected with a hand wheel through a coupling mechanism. Due to the facts that bevel gear transmission is adopted, and the personnel air lock has a manual operation mode and an electric operation mode through electromagnetic clutches and chain transmission, the middle transmission box of the personnel air lock is simple in operation, convenient to operate and powerful in operation, and satisfies needed functional requirements.