Aiming at the problems of low positioning accuracy and complex system equipment of two-dimensional direction finding time difference of single station and three station time difference location model based on external satellite radiation positioning. In this paper , we design a limit constraints time difference of two station location model. using a priori knowledge about the target height information is introduced into the earth position equation, instead of positioning time difference in the model, the three station time difference equation dimension ,solve the two station is conditioned by measuring condition unable to establish an effective positioning equation problem, using Newton iterative method to solve the target position. The high precision target position is obtained under limited conditions. The experimental results show that the parameters such as time difference, distance between station and satellite orbit error have little influence on the positioning accuracy, and the relative positioning accuracy of each parameter is better 0.2%R. This positioning method has good application value in engineering.