Abstract: In order to judge the overall desorption appearance time in the coalbed methane well, based on the numerical simulation software of the oil and gas reservoir, taking the typical well A Block in Qinshui Basin as the original type, an ideal numerical model of the coalbed methane was established and was applied to analyze the relationship of the overall desorption appearance time to the permeability, porosity, seam thickness, critical desorption pressure and others. The results showed that when the overall desorption was appeared, the water yield degree from the strata was related to the porosity and the critical desorption pressure, but was not related to the permeability and seam thickness. When the overall desorption was appeared, the relation board between the strata water yield degree and seam properties was firstly formed. With the relation board, the researchers could rapidly judge the coalbed methane well whether realize the overall desorption or not and the relation board could have certain guide function to the high efficient development of the coalbed methane.