The invention provides a semiautomatic assembly system and a control method thereof. The system is constituted by a power source, an automatic clutch, a manual transmission and a power assembly controller, compared with a traditional assembly, a driver's operation strength is greatly reduced, compared with a new energy power assembly, the structure is simple, and the reliability is improved. Besides, aiming at starting control of the semiautomatic assembly system, the automatic clutch is controlled to be separated simply by starting a gear shifting handle, the automatic clutch is controlled toapproach a slide friction point simply after a starting gear is engaged, after a hand brake and a brake are loosened, a press disc and a driven disc of the automatic clutch are controlled to be combined through accelerator openness, comfort and power of starting are both considered, and the semiautomatic assembly system also has a vehicle slope slip prevention function. Aiming at gear shifting control of the semiautomatic assembly system, the automatic clutch is controlled to be separated simply by starting the gear shifting handle and is controlled to be combined simply after the gear is shifted. In the gear shifting process, the gear shifting operation process of a manual shift gear is fully reserved, and the driver cannot be perplexed.