Forest fire simulation tests were performed with polymer and porcelain insulators at GOCHANG Power Testing Center. These tests consisted of open flames causing a temperature rise of up to $600{sim}800^{circ}C$ measured at the insulator surfaces. Mechanical and electrical characteristics such as the specific mechanical load, the low frequency dry flashover voltage and the impulse flashover voltage were analyzed for the polymer insulators before, during and after the simulation tests and then compared to the porcelain insulators. At the end of the fire simulation tests, there was no detrimental deterioration of any of the insulators. All the insulators passed the KEPCO specification criteria. This study showed that the forest fire simulation had no impact on the polymer insulators.