Abstract: Abstract: The accurate calculation of deep coalbed methane (CBM) gas content is an important part of its resource evaluation. Based on the literature research, the characteristics of deep CBM gas content are analysed, the existing methods for calculating CBM gas content are summarized, and the main development direction of the calculation methods for deep CBM gas content is proposed through the comprehensive evaluation of each method. Previous studies have shown that deep coal seams usually have higher gas content because of large buried depth, high metamorphism degree and weak hydrodynamic conditions. With the increase of depth, the gas content of coal seam shows a change characteristic of initially increases and then gradually decreases, and the gas occurrence state gradually changes from adsorbed gas to the coexistence of adsorbed gas and free gas. According to the measurement process and gas occurrence form, coal seam gas content can be directly and indirectly calculated, and the calculation principle of each method is different, and the effect and applicability of the deep application are also different, among which the operation procedure of sampling and the accurate establishment of mathematical models are the key to the determination of deep CBM gas content. The development of multiple disciplines, the comprehensive application of various methods, the development of new prediction methods and testing techniques, and the improvement of dynamic and real-time prediction level are the main development directions of deep CBM gas content calculation.