In this contribution, influence of dry bands on electric field distribution on a polymeric insulating surface has been carried out using Finite Element Method. Formation of dry bands on insulating surfaces result in electric field enhancement leading to surface discharges, dry-band arcing etc. which in turn affects the long term performance of the insulators. Hence, in the present work, a polymeric insulating surface is modeled as sheath model using Comsol Multiphysics software. Electric stress analysis is performed in presence of dry bands of different length and at different locations on a contaminated insulating surface. Moreover, the effect of different contamination levels on electric field distribution in presence of dry bands have also been investigated.