The invention discloses a transmission connecting device. The device comprises a driving wheel (2) connected with an output shaft of a power machine (1), and the driving wheel (2) is connected with a driven wheel (4) through a transmission mechanism (3); the driven wheel (4) is fixedly connected with a chuck (5) coaxially, and the chuck (5) is connected with a working machine (6). Through the transmission connecting device, labor intensity for test run and cost for test run are reduced, and the transmission connecting device is simple in structure, convenient to operate, high in practicality and economical performance and capable of being widely applied to various mechanical equipment maintenance plants.