To improve calculation performance of centralized target tracking system which consists of multiple dissimilar sensors, a fusion tracking method based on equivalent sensor was presented. It was assumed in the method that all characteristics of a target could be observed by each local sensor, and characteristics which could not be observed actually were treated as outlier and reconfigured by using state estimate of the target from fusion center, and then measurements with different dimensions from dissimilar sensors were mapped to corresponding measurements of equivalent sensors on system observation space with same dimensions. Therefore, combined measurement filtering method could be adopted to overcome the shortcomings of current centralized fusion tracking method and reduce calculation costs. Experiment results show that tracking accuracy of the method presented is consistent with that of current method, but calculation cost is lower than that of the latter and hardly increases with the amount of sensors.