Abstract: Our research directed towards the analysis and the prevention of the desert and marine effects pollution on ectric insulation in the electric transmission lines power. The fundamental objective of this research is to mprove the service quality by decreasing the interventions frequency and by minimizing the maintenance cost of the equipment line. While basing on theoretical models and the in-situ tests, we present research results on the pollution of the Medium voltage insulators in the areas desert at the Tunisian Sahara.