Abstract: The CMOS TDI of infrared detector based on bucket-brigade device (BBD) structure, has been widely used in the field of space remote sensing, it can compatible with the general CMOS process, and improve the signal-to-noise ratio (SNR) of the system. Compare with the analog TDI, the Digital Time Delay and Integration (DTDI) based on the infrared focal plane array is still in the initial stage. In this paper, the 320256 MWIR FPA was used to do the DTDI research, and the electron transfer efficiency, the BBD noise and the dynamic range of the analog TDI was in a detail analysis to compare with DTDI. And the NU and blind pixel were also taken into consideration to analysis the DTDI performance. Finally in the experiment, the SNR can be increased to 2.5 times and the NU can be reached 1.68% after the 16-stage DTDI was used, which verify the improvement of the system performance by using DTDI technique.