In order to improve the dynamic response performance of LCC-HVDC transmission system, a controller parameter optimization method based on small-signal dynamic model and transfer function model is proposed. Firstly, a small-signal dynamic model of double-terminal LCC-HVDC transmission system considering the difference between the output phase of the PLL and the actual phase of the AC bus voltage is established, and the simulation results verify the accuracy of the small-signal dynamic model. Based on the root trajectory method, the critical value of the control parameter that causes the instability of the system with small disturbance is obtained. Finally, the small-signal dynamic model is transformed into the transfer function model, and the particle swarm optimization (PSO) algorithm is applied to optimize all the controller parameters by taking the integral of time multipled by the absolute value of error (ITAE) index as the objective function. The simulation results show that the dynamic response performance of the system is improved after optimization.