Abstract: Multi-GNSS combination is helpful to improve the accuracy and relibality of satellite navigation and positioning. However, in case of BDS/GPS combined carrier phase positioning systems, it is difficult to fix all the ambiguities due to the increasing number of ambiguities, high measurement noises or residual atmosphere delays with the traditional Lambda method. But it is of greater probability to fix a subset of ambiguities. In this paper, we divided current partial ambiguity fixing methods into three categories and analyzed the characteristics of every method. Finally, the effect of the three partial resolution methods were tested with the measured BDS/GPS data. The results show that the success rate and ratio value is obviously improved when using partial ambiguity fixing, at the same time, the initialization time of RTK is shortened, the precision of kinematic positioning is also improved.