Abstract: In the application environment of using unmanned aerial vehicle (UAV) formations to locate the fixed target on the ground, which is radiant point, the angle between UAV and the fixed target, which transmit electronic signals, could be detected by using the Electronic Support Measurements (ESM) which carried on the UAVs, which compose the UAV formations, and the coordinate of the fixed target could be calculated by using the arrival of angle which is got by ESMs at each scan time. Suppose the sensors on the UAVs have identical measurement accuracy, and the measurement-error of the ESM is a zero mean Gaussian process noise. Under this condition, the accuracy of co-location would be affected by the formation of UAV formations. In this paper, we researched the relationships between the formation of UAV formations and the accuracy of co-location, which used the method of AOA. At first, we established the co-location model of two UAVs by using the geometry relationship of two UAVs, and derived an error model of co-location with UAV formations which based on the method of direction finding cross location. The second, Analyses the influence of positioning accuracy in different sensors' distance and different combination of azimuth angles by using the error model of co-location which derived at the first stage, Based on the analysis above, We got the conclusions about the relationship between the formation of UAV formations and the accuracy of co-location. Finally, we propose a function of data fusion selection for measurement data based on the method of bearing-only location and use the function to improve the method of AOA location. The validity of the improved method is verified by the results of simulation. At the same time, the conclusions, proposed in this paper, which described the relationships between the formation of UAV formations and the accuracy of co-location could be used in optimal UAV formations path planning.