To build the human contrast sensitivity function based on LCD display in the dark room via the psychological physics experiment. Through testing the auto-correlation value of different color spaces, the color space with minimal inter-channel correlation was chosen. Grating images with different spatial frequency and different contrast were made based on the four chosen color points. A total of 15 people were arranged for observation experiment, and the psychological contrast threshold under different spatial frequency was obtained. The contrast sensitivity function model was then obtained by fitting the threshold data. The CSFs of channel L, channel A and channel B were obtained by fitting. The minimal auto-correlation value of LAB color space was 0.1134, suggesting the best orthogonality. The contrast sensitivity function obtained matched the low pass characteristic of human eyes, so the results of the study will be quite meaningful for improving the color difference model and image compression.