Especially, Fiber glass Reinforced Plastics(FRP) is the best composite insulating material which has been so far. Therefore, it`s worthy of notice to investigate on the corona electrified composite insulating material by surface condition. And then some other materials will be focussed on. In this study, charge decay were measured with charging-time and grid voltage on FRP composite material surface in order to analyze the mechanism. As a result we have studied that the way of the composite glass fiber(GF) and Polymer and the condition of the contaminated surface was different. In case of the GF is mixed with vertical, charge decay speed is fast because the charge is easily leaked. On the other hand, the surface charge decay speed is depend on conductive or insulated of the contaminant.