The observational characteristics of sensors in an electro-optic detect system is analyzed, and then some data aligning methods and data aligning process are introduced, that is a major work in multi-sensor data fusion. Weighted data fusion concept and some fusion criterions of an electro-optic detect system with different testing precisions of sensors are investigated. Target-tracking algorithms based on data fusion criterions are given and simulated. The results show that different fusion criterion is selected for the sensor with different testing precisions to accurately forecast target-tracking, consequently the efficiency and accuracy of target tracking is improved.