When insulators in the transmission line are faulty, the electric field around them will be partially distorted compared to the good insulator strings. Therefore, the electric field distribution characteristics before and after the fault can be compared to recognize the faulty insulators. In this paper, a 1:1 model of 110kV porcelain insulators based on finite element method is established. and the electric field distribution around insulator strings is calculated without a faulty insulator. By changing the different position and degree of faulty insulator, electric field distribution curve around faulty insulator strings is obtained. The simulation results show that axial electric field around faulty insulator decreases and electric field intensity around the zero-value insulator is smaller than low-value insulator. The farther the measurement distance is, the less the distortion of the electric field curve is. Insulators electric field test platform was built in high-voltage experiment hall. The axial electric field of insulator is measured by electric field sensor and the data were processed by "linear normalization method". The test results show that the electric field around low value and zero value insulator apparently decreases, which is agreement with results of simulation, to verify the effectiveness of the changes of the electric field. Therefore, the measurement of space electric field can realize live detection of faulty insulators.