A novel type of automatic transmission named Overrunning Clutch Shift-assistant Transmission (OCT) was designed in the paper, which realized the shifts by the alternative work of friction clutch and Overrunning Clutch. Dynamic model of a 2-speed OCT was built to discuss the driveline vibration during shifts. Control strategy of the friction clutch and power source was presented in this paper, which was also verified by both simulation and test results. The results also show that the control strategy can make both upshift and downshift smooth, and jerk of the shifts is below 10 m·s-3.