Abstract: At present, the X-ray measurement method of coal metamorphism has the problem that the γ band is not well divided, the δ peak information is not used, and the background of the bottom is unreasonable. The X-ray diffraction pattern of coal with different metamorphosed degrees is compared and studied. It is proposed to correct the metamorphic coefficient formula by using the information of the slope of the 002 peak, the extended half-height width and the δ peak without deducting the so-called background information. The calculation of the XRD patterns of coal samples with different degrees of metamorphism is verified. The method can better express the degree of metamorphism of coal, avoid the problem that the γ band is not well divided, the δ peak effective information is not used, and the background is unreasonable. It is a simple, feasible and accurate measure of coal metamorphism. The method of degree is recommended to be promoted in the industry.