Abstract: Under the mixed environment of Line-of-sight and Non-line-of-sight,the question of relatively accurate three-dimensional indoor location is researched by using less base station information.A LOS high-precision differential base station transmission algorithm based on geometric model is proposed.This algorithm constructs the spatial stereo model by simplifying the signal propagation path,and by using the basic geometry theorem,we can select the relative most near LOS signal transmission.Next the algorithm combined with TDOA location algorithm and least square method,get the relatively accurate positioning information.Theory analysis and simulation results show that the algorithm can identify the line-of-sight transmission signalefficiently.Finally,the proposed algorithm is not complicated and easy to realize.