With the large-scale distributed generation equipment gradually replacing the traditional synchronous generator，grid-connected systems are faced with a series of challenges such as loss of inertia，voltage and frequency stability decline. The introduction of grid control technology gives the necessary inertia and frequency support capability to distributed generation equipment. In the field of grid control technology，virtual synchronous generator technology has been widely used，but the traditional proportional integral （PI） control strategy it relies on has some problems，such as weak anti-interference ability and insufficient transient stability. In view of these shortcomings，an improved sliding mode active disturbance rejection control strategy for grid type photovoltaic energy storage system is proposed，which applies to the outer voltage loop of the system to improve the system performance. Among them，the fraction order extended state observer is designed to enhance the observation ability of the internal state of the system，and the fixed-time convergence sliding mode controller is designed to effectively suppress the chattering phenomenon in the traditional sliding mode control by means of its characteristic of converging to the equilibrium point in a fixed time，thus significantly enhancing the robustness and anti-interference ability of the system. Finally，through the construction of simulation model in MATLAB environment and experimental verification，the simulation and experimental results show that the control strategy proposed in this paper effectively reduces the transient voltage fluctuations of the system and speeds up the system response speed，which plays a positive role in improving the system performance.