The invention provides a Haze-deposited-ashes-targeted photovoltaic power generation power output reduction rate estimation method. The method uses PM2.5 cumulative concentration and PM10 cumulative concentration to characterize the deposited ash concentration of a photovoltaic cell panel. On the basis of structuring a large number of actual samples of PM2.5 accumulation concentration/PM10 accumulation concentration/photovoltaic power generation power output reduction rate, the method uses the least squares method to establish a photovoltaic power generation power output reduction rate estimation model, and the model is used to estimate the reduction rate of power generation output of photovoltaic cells under haze weather. The present invention contributes to improving the prediction accuracy of photovoltaic power generation in haze weather.