The invention provides a method of judging whether a component at a place of a photovoltaic power plant is covered with snow. According to the method, daily power generation amount data and meteorological data of the photovoltaic power plant are collected mainly, calculation and processing are carried out, thus the data can be preliminarily screened according to calculation results, then a histogram of the corresponding data is drawn according to preliminary-screening results, and then whether the snow exists on a current day can be judged through analyzing the histogram. The method is simple,easy to realize, high in a hit rate and low in an error rate, and has broad application prospects.