Abstract: To analyse the principle of detection, of actual situation human being is first regarded as a point charge composing a system with the obstacle and air. Based on the principle of static induction a human obstacle is detected. The distribution of human bodys electric field is studied in many types of mediums structure. The point charges calculation of electric potential is given. Two mathematical models of the electrostatic detection people through the medium are established and carried on emulator. It is shown that the thickness of the obstacle and the magnitude of the constant are in inverse proportion to the detection distance and the maximum detection distance can be drawn through models and foregone situations.