Abstract: Based on analyzing and summarizing classification and characteristics of single danger source of coal mine accident,the paper gave steps of calculation and risk assessment of single danger source of coal mine accident.In calculation of single danger source of coal mine accident,it is needed to identify danger source according to single danger source data of single coal mine accident collected and decide characteristics of single danger source,so as to select proper calculation method and thought of danger source to do calculation and do assessment to calculation result.In risk assessment of single danger source of coal mine accident,it is needed to calculate probability and risk probability of single danger source of coal mine accident,do loss assessment to single danger source of coal mine accident,and on the basis do risk assessment to single danger source of coal mine accident and divide danger levels of single danger source according to assessment result,so as to make corresponding measures to reduce probability of accidents caused by single danger source.