Non-uniformity correction of thermal imager is a key technology for thermal imager applications. The common method is a blackbody-based thermal imager non-uniformity correction method. Multiple imaging method can solve the problem that the blackbody-based method is affected by the non-uniformity of the radiation source,but the method correct the non-uniformity using the relative relationship of multiple thermal images,it is difficult to locate accurately in the thermal image coordinates. Based on the principle of multiple imaging method,a non-uniformity correction method of thermal imager scanning blackbody with uniform speed was proposed,which combines the advantages of calibration-based and registration scene-based non-uniformity correction methods. Through scanning blackbody reference source by a thermal imager,the non-uniformity was evaluated by the difference of the response of different detection units to the same scene of the blackbody. Compared with multiple imaging methods,the method in this paper is easier to achieve and has better anti-noise ability. The non-uniformities of the two thermal imagers were corrected by this method. The results show that the non-uniformity of the blackbody can be separated,but the demands about time stability of the blackbody radiation source and the thermal imager are improved.