This article is to research and study the effect of moisture content on the breakdown of insulating air. To use knowledge about high voltage transmission condition with moisture by design, optimum 1.5 X 1.5 X 1.5 meters. This study used the electrode shape and the plane, pointed to a plane, and the plane to plane. By adjusting the distance of the electrode within the laboratory stage, 0.5 0.6 0.7 0.8,,, and 0.9 mm. Let steam or fog into the provincial laboratory, and 70 60 percent, 80 sensors is ordered to create fog machine stopped paying high voltage into the lab to measure the voltage breakdown condition humidity set. The study found that When the humidity inside the lab more affects the voltage breakdown added up. And when adjusting the distance of the gap far more voltage breakdown will increase as well.