Abstract: Definition of early warning of coal and gas outburst was given, and difference between the early warning and forecasting was clearly pointed out. The early warning of coal and gas outburst was classified from angle of space, time and index system, and features of the early warning were put forward according to specific characteristics of coal and gas outburst disaster. System structure and implementation of the early warning were analyzed guided by system theory and accident theory. Steps of the early warning were described from five aspects of detection of risk source, warning sign identification, analysis of warning situation, alert release and early warning response. Method of effect evaluation of the early warning was put forward by using three indicators of initial warning accuracy, false negative rate and false alarm rate. The field application results show that the average accuracy rate of state warning is 89.1%, the average accuracy rate of trend warning is 92.5%, and the false negative rate is 0.