The access of distributed generators to the network of distribution has changed its internal structure and power flow trend, posed a threat to the traditional distribution network relay protection system, and reduced the operational dependability and safety of the entire power system. In this paper, the impact of distributed generators’ access location and capacity on the existing relay protection system of distribution network is analyzed from the current passing through the area of protection while failures with three-phase short circuits happen at several places, and MATLAB/Simulink serves as the foundation for the simulation model to take the three-phase short circuits fault for a special example. In view of the effect of access to the protection system’s distribution network via distributed generation, a master protection strategy on the basis of adaptive current protection based on composite sequence components was proposed.