A method for drawing a real-time dynamic three-dimensional power grid contamination area distribution diagram includes the steps of S1, establishing a corresponding relation between air pollutant concentration and the gradation for surface pollution, and S2, drawing the contamination area distribution diagram. The S2 further includes the steps of S2-1, conducting square mesh generation and rasterization processing on an object region, S2-2, reading real-time air pollutant concentration, S2-3, calculating the air pollutant concentration, S2-4, reading the position, the discharging type and the discharging amount of pollution sources, S2-5, reading the data of wind directions, wind speeds and rainfalls, S2-6, checking and amending the air pollutant concentration by the aid of the data obtained in the steps (4) and (5), S2-7, dividing the gradation for surface pollution and coloring according to the corresponding relation in the S1, S2-8, making a clustering analysis and denoising, S2-9, conducting vectorization and smoothing, and loading DOM, DEMs, power grid device information and the pollution sources to a three-dimensional GIS platform, S2-10, repeating the steps from (2) to (9) for 5-60 minutes to form the dynamic contamination area distribution diagram.