Coalbed methane content is an important indicator of CBM resources assessment，development deployment and economic evaluation. By analyzing a large number of experiments，the main controlling factors of the coalbed methane content in Block XX of Kgalahari Basin were studied. The studies show that the vitrinite in organic macerals of coal experienced the gelation function and the inertinite experienced the silk-coalification function. The coal rich in vitrinite has higher methane content and stronger adsorption ability，while the coal rich in inertinite has lower methane content and weaker adsorption capacity. Coal rank controls the production of coal-bed methane and the development of coal reservoir pore and cleat. When the vitrinite reflectance（Ro）is less than 0.5%，a small amount of biogenic gas is generated and the primary pore is well developed in coal. The adsorption ability of coal seam is poor and the content of coalbed methane is low. When the Ro value ranges from 0.5% to 4.0%，the organic matter experiences thermal degradation and thermal cracking，a large quantity of methane was generated. Along with the increasing of the Ro values，the degree of micropores and cleats development in coal increase gradually as well as the specific surface and the gas content. When the Ro value is above 4.0%，the degree of micropores and cleats development in coal decreases as well as the specific surface and the gas content. Coal ash is negative correlated with coalbed methane adsorption capacity. When the coal ash content is less，the adsorption capacity is stronger and the coal bed methane content is higher. Good preservation condition can be achieved when the rock in coal seam roof is dense and low in permeability and the wells are far away from the fault，and thus the coalbed gas content is relatively high.