Regarding the active lane-changing scenarios of intelligent vehicles in multi-lane urban road traffic situations，the sole use of a single control algorithm for active lane-changing path tracking may lead to issues such as reduced path tracking accuracy or vehicle handling stability. This paper proposes a decoupled lateral and longitudinal lane-changing trajectory tracking control strategy. Firstly, the trajectory tracking control is decoupled into lateral position tracking and longitudinal speed control. Subsequently, a feedforward plus feedback lateral controller is designed based on the discrete LQR principle, and a position and speed longitudinal controller is designed based on the dual PID principle, ultimately achieving tracking control of the planned trajectory. Finally, a co-simulation model is established using Matlab/Simulink, PreScan, and CarSim platforms for simulation testing. The results show that the decoupled lateral and longitudinal trajectory tracking control algorithm performs well in tracking the trajectory under different lane-changing conditions of the vehicle, with the tracking control errors of the vehicle all within the specified constraints. Moreover, compared to the MPC controller, it has a smaller centroid sideslip angle and yaw rate, offering better driving stability and comfort.