Abstract: In this paper,the influence of different particle sizes and different components of ash deposition on the output performance of photovoltaic modules is studied. Based on the experimental data,the fitting model of ash deposition density,solar irradiance,photovoltaic module output power and working current is established. The experimental results show that the open circuit voltage and the optimal working voltage of the photovoltaic module are less affected by the ash deposition property,and the optimal working current of the photovoltaic module is greatly affected by the ash deposition property. The maximum output power attenuation of the photovoltaic module is mainly affected by the decrease of the optimal working current of the photovoltaic module. The influence of the ash particle size distribution on the maximum output power and the optimal working current of the photovoltaic module is much greater than the influence of the ash composition.