As cloud parameters are important input parameters for retrieval of trace gases, it is of great significance for their accurate acquisition. Based on environmental trace gas monitoring instrument (EMI) observation on March 2019, the effective cloud fraction is retrieved by using the absorption feature of O4 at 477 nm. To verify the accuracy of EMI cloud algorithm, the retrieval cloud fraction of EMI is compared with TROPOMI cloud products, and the correlation analysis of EMI and TROPOMI cloud fraction on March 2, 6, 9 and 10, 2019 is carried out, and the cloud fraction correlation coefficient (R) is 0.752, 0.712, 0.764, and 0.762 respectively, indicating that the two results have good correlation. Furthermore, the cloud fractions of three different regions of desert, ocean, and land are selected to study the distribution characteristics of cloud fraction in different underlying surface. It is found that the cloud fractions of EMI and TROPOMI in the three regions are consistent, and the cloud fraction over the ocean is relatively low, the cloud fraction over the land is relatively high, and the cloud fraction over the desert changes frequently.