<p>In order to effectively identify degraded porcelain insulators in transmission lines and ensure the stability of power system operation, this study proposes a method for identifying degraded porcelain insulators in transmission lines based on spatial electric field distribution environment. Maxwell’s equations are used to analyze the basic principles of electric field distribution measurement methods. Using COMSOL finite element numerical calculation software to construct a simulation model of the electric field of porcelain insulators in transmission lines, and obtaining the spatial electric field distribution curve of the undamaged insulator string. Subsequently, simulation tests were conducted by changing the location and degree of degradation of the insulator string to obtain the curve under the degradation state. The simulation results show that the axial electric field strength in the degraded area of the insulator string is significantly reduced, and the reduction degree of zero value insulators is more prominent than that of low value insulators. Based on this, an insulator spatial electric field experimental platform was built in the high-voltage experimental hall, and photoelectric field sensors were used to measure the axial electric field of insulator strings under different conditions. The measurement data was processed using linear normalization method. The experimental results are consistent with the simulation, and the axial electric field distribution curve can be obtained from the results, which can be used to identify degraded ceramic insulators.</p>