Summarizing main methods of MRTD-testing for thermal infrared imager briefly. For the requirements of MRTD real-time measurement in engineering, the mature objective MRTD method with less manpower and less measuring time is adopted. While ensuring measurement accuracy, optimizing the measurement steps、 improve the method of eigenvector abstracted and significantly reduce the measuring time, the improved method is more suitable for engineering measurement. Compared the subjective measurement method with the improved objective measurement method, the obtained measurement results are well consistent. and the factors of influence on accuracy of objective measurement were discussed. The given method provides an effective means for MRTD engineering measurement.