The engine brake characters and its influence factors are introduced, and the experiment of engine brake performance is expounded. The necessity of control continuously variable transmission (CVT) ratio during engine braking is discussed. When engine braking, the engine brake torque based on object velocity is estimated. With the characteristics curve of the engine brake torque and engine speed-brake torque, the object speed is gained. Then the object ratio is calculated through the engine target speed and target velocity, and PID algorithm is used for tracking the object ratio. Finally, the simulation result shows that the CVT ratio control strategy is valid.