Although live working in the process of power grid operation and maintenance ensures the uninterrupted operation of power grid, it also increases the risk of operators and mechanical equipment compared with traditional methods. Real time and accurate monitoring of the electric field environment and real-time alarm to power personnel when the electric field is too strong are of great significance to the safety of power personnel. Taking 110 kV transmission line as an example, the influence of live working human body on the measurement of high voltage power frequency electric field under the limit safety distance by finite element method is studied in this paper. The differences of electric field measurement with and without human body in the upper, lower and side directions are compared, and the differences of electric field in different body parts of live line workers are calculated. The maximum difference of electric field measurement with or without human body in the three directions can reach 183.08%. Therefore, the electric field alarm device should consider the influence of human body on electric field distortion and the monitoring direction and position of human body to correct the alarm threshold.