Abstract: The wavelet covariance transform method was used to dervive the height of the ABLT from refractivity profiles. COSMIC refractivity data from 2007 to 2012 was used in an analysis of the spatial, seasonal, and diurnal variations in global ABLT parameters. The results show that the latitudinal and longitudinal variations of the ABLT parameters are distinct. Under the impact of atmospheric dynamic factors, the amplitude of the seasonal variation over land area is greater than that over ocean area in the 30°S to 30°N range. ABLT temperature and ABLT height are positively correlated over 40°S-90°S and 40°N-90°N ranges, and is negatively correlated over the 30°S~30°N range.The ABLT height in 2008 and 2011 were found to diverge from the monthly means for six years. The mean diurnal variation amplitude of global mean ABL depth in 2012 is 0.37 km. The diurnal variation of ABL depth over land and sea areas of the same latitude is correlated to each other to some extent.