For the least-square solutions of two positioning models in single-point position, the equivalence proving of position estimation and its precision is given. The basic positioning model and single-difference positioning model were described respectively, then the single-difference positioning model was arranged into three cases, and the least-square solution of each case was proved equal to that of basic positioning model. Finally, the equivalence of the two models was proved by processing the experiment data, and the efficiency of least-square arithmetic for the two models was compared with each other.