Abstract: When using the direct method to measure the gas content in coal seam,the most difficult to control and the largest error is gas loss quantity calculation.At present,using the graphic method and the least squares method to calculate the loss quantity of gas are the most commonly method.In this paper,two methods were used to calculate the gas loss quantity in measuring coal seam gas content,and the results were compared and analyzed.Then on the basis of statistical measured data,the influence of the two methods on the accuracy of gas loss quantity was analyzed and compared.