Zero value insulators threaten the safe and stable operation of transmission lines. Using the fiber optic electric field detection method，the local electric field distribution of insulator strings can be quickly detected，thereby identifying zero value insulator piece. A fiber optic electric field detection tracked robot is designed. To analyze the possible errors and impacts of fiber optic electric field detection robots during the detection process，an identification criteria is proposed. A true model of 220 kV insulator string and an equivalent model of fiber optic electric field detection robot are established. The electric field distribution characteristics of the robot architecture at different positions of the insulator string are simulated and analyzed. The influence of factors such as robot material，position，and size on the characteristics of local electric field distortion has been studied，especially the changes in local electric field under zero and non zero values. The research results reveal the influence of the fiber optic electric field detection robot on the local electric field distortion of zero value insulator，and thus provides technical support for the intelligent operation and maintenance of external insulation in power transmission and distribution.