In the case of distribution network failure, the output current of photovoltaic power plants which have capability of low voltage ride-through (LVRT) is closely related to the PV capacity, fault type and fault location. It brings great difficulties to the current protection of distribution network. The characteristics and control strategies of low voltage ride-through of PV are analyzed. A fault analysis method of distribution network with PV is proposed. Based on the failure characteristics of distribution network with PV, the problem of adaptive current instantaneous trip protection in distribution network is analyzed. Because PV only output positive sequence current, an adaptive positive-sequence current instantaneous trip protection for distribution network with PV is put forward. A 10 kV model of distribution network is established by using PSCAD, verifying the correctness of the protection.