Monostatic surface wave radar is vulnerable by the threat of stealth targets and establishment of near space bistatic radar is the most achievable way to solve this problem. The positioning principle and accuracy in near space bistatic radar is discussed in this paper. The geometrical dilution of precision expression of single measurement subset is calculated. The position precision contours of measurement subsets are obtained and which subset can be chosen for positioning at different area is pointed out. Simulation results show that different subset has different position accuracy and a high accuracy subset distributing picture is presented. Research of this paper provides a theoretical base of detecting and tracking for near space bistatic radar.