In this paper, a parameter setting method of grounding distance protection for transmission line based on positive sequence impedance is proposed. By analyzing the ratio of the inductive impedance and positive sequence impedance in extreme cases, the setting value can be obtained directly from the positive sequence impedance to realize the decoupling between the setting value and the line mutual inductance, simplify the setting principle of distance protection, and realize the transformation of setting calculation from complicated short-circuit current calculation to simple parameter setting. This paper analyzes the location of each section of distance protection, and puts forward different setting strategies for the same tower line and the non same tower line from the perspective of engineering application. Finally, an operation line example is given to show that the method is simple and feasible, and has strong adaptability and engineering practicability. Based on this method, a prototype of line protection device has been developed and applied to Guangdong Power Grid.