Abstract: As an ideally controlled starting device for heavy scraper conveyer, valve-controlled fluid-filled hydraulic coupling boasts such advantages as improving starting performance and stepless speed regulation. To predict the soft start-up performance of hydraulic coupling working with three-phase asynchronous motor, the pump wheel torque characteristics of the coupling are obtained based on the simulation software ANSYS-CFX. The input characteristics of the motor and hydraulic coupling are jointly analyzed. On the basis of the matching principle, the common working points of the two under different liquid filling rates and different speed ratios are determined by using matlab software. The output characteristics of the joint operation of the hydraulic coupling and the motor under full and partial filling conditions are obtained. The results show that under different filling rates, the output torque of the hydraulic coupling and the motor working together decreases with the increase of the output speed on the whole, and goes up with the rise of the filling rate. When the output speed is low, the torque values at 90% and 100% filling rates remain stable. Comparing the output torques when motors work together or start directly, the changes of the former experiences are more smooth. The research may provide references for the study of soft start control strategy of scraper conveyor.