The FY2 geostationary satellite spectral data consist of several detection channels, including visible, water vapor, mediumlong wavelength infrared and multichannel. Among these channels, the multichannel data can provide satellite cloud top temperature data. This paper, based on FY2F satellite cloud top temperature data, combined with the local realtime ratiosonde data, retrieves the cloud top height from the satellite data of clouds over the southern suburbs of Beijing and makes comparison with the groundbased millimeterwave cloud radar detection of cloud top height to analyze the cloud top height observation results under the three kinds of cloud thickness. The results indicate that the match degree of two sorts of measurements is affected by the geometric cloud thickness, and the coincidence degree shows the best for thick clouds and the worst for thin clouds.