Abstract: Aiming at the problem that dissolved gas content and free gas content can not be calculatd by lost gas content, based on gas logging data, a new method, named total degassed hydrocarbon analysis, was proposed for computing lost coalbed methane. In the practical application of the method for the No.3 coal seam in Qinshui basin, it was found that the lost gas content obtained by this method was significantly higher than that by conventional coal core sample regression method, and the former is generally 1.5 to 4.5 times higher than the later. In one hand this method can not only effectively solve the problem ignoring of dissolved gas and free gas in coalbed gas content calculations, but also eliminate the impact of lost time. In addition this method is able to calculate the lost gas for different coal seam parts. This method is promising in lost gas calculation because it is easy to collect data, has simple calculation process and is widely applicable in coal with different rank and various structures.