The connection of distributed generation (DG) will change distribution network form single-source radial network to multi-source network, as well as the distribution of power flow leading to unreliability of the relay protection. According to the impact of DG connection on the relay protection of distribution network, a method was proposed for fault isolation and service restoration using directional pilot protection and over-current protection. This method can solve DG connection problems and improve the efficiency of DG utilization. Power system simulation software PSCAD/EMTDC was used for the simulation of 10 kV distribution network, whose results proved the method's effectiveness and correctness.