Abstract: This paper establishes a computational model of Post insulators using COMSOL multi physics simulation field software. Using parameters such as umbrella extension and umbrella spacing as variables, the parameterized scanning method is used to analyze and calculate the electric field distribution of Post insulators. The results show that the average surface electric field strength of the post insulator is inversely proportional to both umbrella extension and umbrella spacing, while the maximum electric field strength is inversely proportional to the umbrella spacing and directly proportional to the umbrella extension. Moreover, as the equivalent diameter of the umbrella skirt increases, the maximum electric field strength at the end of the insulator also increases. Simply increasing the creepage distance may reduce the insulator's ability to resist pollution flashover. The accident case shows that the grounding knife switch insulator that experienced flashover had three fewer umbrella skirts than the conventional insulator. To meet creepage distance requirements, designers increased the diameter of the umbrella skirts. This resulted in a 26.19% higher potential difference between the first and last umbrella skirts compared to the conventional insulator, along with a higher overall electric field strength. Its ability to withstand pollution flashover was lower than that of the conventional insulator.