Abstract: The determining of time and intensity of heating is on important problem of thermal wave NDT with uniform heating. In this paper, numerical computing was used to simulate the process of heat conduction in material with defect and to study on changing orderliness of temporal spatial thermal distribution. Observing and analyzing the result, conclusions are as follows: in given conduction, the rate of changed tmperature of any part of heated object and heat flux is a constant; when heating time is long enough(the time is not related to heat flux), the rate of changed temperature of any part of object is a constant. These phenomena show the relationship between the biggest temperature contrast and heat flux, which provides theoretical basis to determine intensity of heating and optimize the parameter of heating and lay a foundation for quantitative testing and evaluation of thermal wave NDT.