A fusion method of multi - sensor data is presented based on gray incidence analysis. The process of this method is to compute the gray incidence matrix of multi - sensor data, to analyze gray superior, to make the multi - data fusion. In the method the influence of each sensor's precision is taken into account and the precision lower data and the data can not be obtained by measurement are deleted. The simulation result indicates that the reliability and tracking precision of fusion system can be improved by using the method. It is suitable for the multi-sensor data fusion.