In order to explore the visual contrast effect of OLED and Mini LED display under different ambient light intensity, the parameters are measured and verified from the perspective of environmental contrast and human eye perception. We analyze the contrast performance of two display technologies in darkroom, 100 lx ambient light and 450 lx ambient light. The test results are discussed by correating with the theoretical simulation calculation. The rationality of environmental contrast is analyzed from the perspective of human eye perception. Based on human factors experiment, the equal perception contrast is studied. The experimental results show that the environmental contrast is not consistent with the perceived contrast of human eyes. To describe the perceptual contrast, we should not only focus on the brightness ratio of black and white pictures, but also consider the brightness of black field and white field. In a dark room or an ambient light of 100 lx or 450 lx, the Mini LED can achieve a visual contrast effect similar to OLED by increasing the brightness of all-white field by 1~1.7 times.