Abstract: Non-uniformity correction (NUC) of 2nd generation scanning thermal imager usually utilizes the fixed two-point temperature calibration method or the fixed multi-point temperature calibration method. However, the fixed-point correction cannot adapt to the changes of the detectors caused by the environment or time, hence the calibration parameter is deviated and the space errors increase. We put forward a kind of real-time correction method by setting two controllable temperature blackbodies in the light path ,and the temperature of the blackbody always followed that of the scene in real time. So the correction parameter was updated in real time to effectively reduce the output error. With some contrast tests of the different scenes, results show that for the traditional fixed point correction, the size of the nonuniformity noise is about 4.0, while adopting the method of this paper, the size of the noise is not greater than 2, effectively reduces 50%.