In an exterior ballistic measurement system, data fusion for optical measuring equipment and radio exterior trajectory measuring system is very effective to improve the comprehensive precision of target measurement and the utilization rate of instrumentations. According to a joint positioning model with photo-electric theodolite and nearby radar, data fusion of the angular-position data obtained from theodolite and the ranging data obtained from radars will be implemented by using total differential formula and the difference of measuring station sites. It is natural to figure out the target′s azimuth and pitching angle, and then the target′s three-dimensional position in space. The main error sources of the positioning model are analyzed, as well as their influence for positioning results. The analysis results show that the joint positioning accuracy of photo-electric theodolite and radar has an advantage over the accuracy computed by single radar positioning data. The precision of the joint positioning method is within 2 m, which is an obvious expression of the high angular measurement accuracy of photo-electric theodolite and high range measurement accuracy of radar.