Because it is difficult to obtain the priori position for time-free positioning algorithm, the coarse-time GPS(Global Positioning System) positioning algorithm with ambiguity search was proposed. Four satellites, which are the most reasonable combinations based on minimum root mean square of residuals criterion, were selected for coarse positioning by iterating through all combinations of integer ambiguity. The full pseudoranges of all satellites were constructed based on the priori position. The position was estimated using time-free positioning algorithm. The performance of the proposed method was verified by using the observation data of 11 IGS(International GNSS Service) stations. This method can achieve coarse-time GPS positioning even if the priori position is unknown, and provides comparable positioning results as compared with the traditional precise-time positioning. 