When the ground-based pseudolite navigation system is used for vehicle, there will be some bad geometric configuration situations because of the area restriction for pseudolites. If the traditional single positioning algorithm is used with pseudo range only as usual, the precision of positioning for vehicles will be low. In light of this, this study proposed that the inaccurate solution of receiver’s clock error affects the precision of positioning to a great extent. For this situation, an improved approach was suggested to obtain a better precision of positioning through increasing the accurateness of solution of receiver’s clock error. The main idea was to obtain the observation model of the receiver’s clock error and then adding the model to the positioning equations. The simulation results indicate that the approach is feasible and effective.