When ground faults occur on transmission lines， zero sequence currents of both ends will be very different from each other if there is a significant difference between the zero sequence impedance of both ends. Pilot zero sequence directional protection may fail to operate because the zero sequence current on one end does not reach the set value of the protective relay， although zero sequence directional elements on both ends operate correctly. This paper performs a simulation analysis on the phenomenon of zero sequence weak-infeed and an improved scheme of pilot zero sequence directional protection is proposed to address this problem. The result of real-time digital simulation demonstrates that the improved scheme can handle the miss operation problem due to the phenomenon of zero sequence weak-infeed and effectively improve the performance of pilot ground fault protection.