Abstract: The influence of the electrode and earth on the electrostatic field of the target is investigated, the aerial electrostatic target, detecting electrode and earth are regarded as an integral system; the model of the passive ground electrostatic detection system with the spherical electrode is built by using the charge mirror method. The theory analysis and calculated results demonstrate that the electrode lower erection is beneficial to increasing it's output. Because the iterative formula of the detection system model is not suitable to practical applications, the reduced system model is deduced, and the calculated results show that the reduced system model coincides with the model of the passive ground electrostatic detection system, which provides a basis for the subsequent orientation of the aerial electrostatic target.