S：Aiming at the problem that traditional three-stage current protection is difficult to be applied after inverter interfaced distributed generation(IIDG) T-shaped access to distribution network, a pilot protection scheme for IIDG T connection distribution network is proposed. The effect of constant power control strategy on fault output during low voltage crossing is discussed. Secondly, by defining the composite differential impedance and analyzing the amplitude difference of the fault in and outside the protected feeder area, the pilot protection principle of the inverter interfaced distributed generation T connection network based on the composite differential impedance is proposed. At the same time, in order to eliminate the dead zone in the three-phase gold short circuit fault, the differential current protection of T-type transmission lines is introduced as the auxiliary criterion. Finally, a 10kV distribution network simulation model with IIDG is built on the PSCAD / EMTDC simulation platform. The simulation results prove that the scheme is reasonable and effective.