The influences of the pollution layer parameters including; conductivity, position and length on the performance of high-voltage cylindrical insulator were investigated. Parameters effects and their interactions have been assessed and determined using the variance statistical technique and the relation between parameters and the flashover voltage, maximum electric field and the breakdown strength is modeled by the response surface methodology (RMS). The 3D model from Comsol Multiphysics was used for modeling and the FEM method was utilized for simulations. The findings demonstrate that the flashover voltage of the non-uniformly contaminated surface is primarily affected by the pollution layer length. Simulation results show that the intensity of the electric field rises with the increasing in length of pollution layer and its position. It was noted that the experimental tests in laboratory for non-uniform contamination are in strong alignment with simulation studies. The results of this analysis should expand our understanding about the performance of outdoor insulators under specific contaminated conditions. The knowledge gathered can be used to enhance the configuration of insulators used in contaminated regions and it is believed that the current study has resulted methodology to estimate reliably and realistically the pollution performance of cylindrical porcelain insulators.