Abstract: Based on system sensitivity theory and system error analysis theory,by introducing the relation between radiation transfer coefficient and angle factor,a computational method,which computes system temperature error about unite surface's absorptivity is developed.Taking the(example) of radiation transfer among surfaces inside a cubic,system temperature error is computed by the computional method.It shows that system temperature sensitivity has higher precision,and experimental time influences on system statistical temperature error.If standard deviation is(smaller),ratio of system statistical temperature error is equal to ratio of system temperature(sensitivity).