The invention discloses a testing device of resistance and electrical resistivity of insulation in high temperature condition. The testing device of resistance and electrical resistivity of insulation in high temperature condition comprise a high-temperature electric resistance furnace, an inner screening box made from ultratek is arranged in the high-temperature electric resistance furnace, an outer screening box is arranged on top of the high-temperature electric resistance furnace, an amphenol connector structure is arranged in the outer screening box; a three-electrode module link connected with the amphenol connector structure is arranged in the inner screening box, wherein the three-electrode module is an alumina ceramics base, which has platinum clad layer, and the amphenol connector structure is cascaded with three coaxial compartment linkers, a megger and a DC stabilized power supply. The testing device can measure resistance and electrical resistivity of insulation in temperature of 800 DEG C in high temperature condition, and can improve measurement accuracy of the testing device.