Abstract: Data from the microwave limb sounder (MLS) has better vertical resolution and inversion accuracy but intersects with measurements of pollution in the troposphere (MOPITT) data from the upper troposphere-lower stratosphere (UT-LS) region. In this paper, we compare MOPITT CO data with MLS CO data at 200 hPa. The results indicate that the CO distributions of both are similar in the middle and low latitudes, and high CO concentrations occur in Midwest, South-Central, and South-East Asia. In general, the concentration values of MOPITT CO are higher than those of MLS, and MOPITT CO shows a global system bias of about 35 ppb (10^-6) at low latitudes. The difference between MOPITT and MLS CO values was analyzed using CALIOP cloud data, and it was found that the occurrence of high CO concentration zones is related to strong convection.