The trap states at the interface between perovskite and charge-transport layer have a great influence on the performance of perovskite solar cells. Here, a high efficiency MAPbI3-xClx perovskite solar cell has been demonstrated, by introducing a thin layer of LiF or PbF2 between the SnO2/perovskite. Improved charge collection and reduced interfacial charge recombination are realized, leading to remarkable rises of both open-circuit voltage (Voc) and short-circuit current (Jsc). This successful interfacial passivation paved a new way to fabricate high performance perovskite solar cells with large Voc.