Multipath interference was one of the main error in GNSS. From the multipath signal characteristics, analysed the effect of multipath interference on carrier tracking loop and code tracking loop. And the anti-multipath performance with vector tracking loop(VTL) was studied. By analyzing the structure of VTL and scalar tracking loop(STL), a linear system model was established, and the effect of code tracking error on VTL was deduced. In VTL, the affected channels were assisted by other channels, weakening the multipath positioning errors. One and more affected channels by multipath had been established. Under these scenes, the simulations had been made to compare the positioning errors between STL and VTL. The experiments proved that, relative to the STL, the fewer affected channels, the better the anti-multipath performance with VTL. And when all channels are affected by multipath, the positioning accuracy of VTL is not worse than the STL.