Abstract: A new active power automatic control scheme for wind/photovoltaic power generation system is proposed to solve the problem of shortage of power resources and poor control, which is based on time domain analysis and cross weight correction algorithm, the reactive power loss of the whole automatic control system is greatly reduced. In this study, Siemens PLC is used to control the substation, which can control the running state of the system in real time, solve the stability problem of the system through time domain analysis, and complete the active power control of wind/photovoltaic power generation by taking into account the cross weight correction algorithm. Finally, based on the sensitivity data, through Matlab simulation, the two active power control systems are compared, and it is found that the active power output of this study is more than 20% higher than that of the traditional method, which increases the competitiveness of wind/photovoltaic power generation system in the electricity market, the feasibility of the design is proved.