In the interest of expanding our observation of long wavelength spectral range based on space, we have designed and implemented a CMOS LWIR Imaging system by using time delay and integration (TDI) arrays with a 480 line of 6 stages. In the hardware design we pay much emphasis on how to reduce noise and improve signal to noise ratio (SNR) of infrared system. The software of host computer realizes non-uniformity correction of line-scan images. This paper presents each part of the system design in detail and preliminary results of tests and imaging. Experiments show that the long wavelength infrared CMOS TDI imaging system has a good performance in terms of SNR and images uniformity.