With the growing of energy crisis, the shortage of power supply in some areas and the unreasonable distribution of energy, it is urgent that the PV power station is connected by Voltage Source Converter-High Voltage Direct Current (VSC-HVDC). Firstly, the whole start-up control process of the grid-connected system is studied and obtained, and a start-up control strategy combining the constant AC bus voltage control with the constant DC/DC voltage-slope control is proposed to alleviate the impact on itself and the grid due to the large fluctuation of the current and voltage at the start-up of grid-connected system. The simulation results show that the combination of the start control process and control strategy can achieve the system start-up without impact and go normally into the rated operating conditions and stable operation. Then, according to the characteristics of the randomness of light intensity, a hybrid particle swarm optimization algorithm is proposed to optimize the controller of the grid-connected system and stabilize the power fluctuation when the PV power station is connected. The simulation results show that the algorithm is superior to the single particle swarm algorithm, and the effect of stabilizing the output power fluctuation of the PV power station is more remarkable. This work is supported by National Natural Science Foundation of China (No.61164010).