Abstract: The alteration of coal caused by different types of magma intrusion into coal-bearing strata is common and complex. The influence mechanism of diabase intrusion on the quality, mineral composition and trace elements of low-sulfur coal needs to be studied in depth. In this paper, the coal No. 7 (low-sulfur coal) of the main coal seams in Liudian Coal Mine of Huaibei was taken as the research object. The influence of diabase intrusion on coal quality, mineral composition, and toxic trace elements of low-sulfur coal were discussed comprehensively by using X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray fluorescence spectrometer(XRF), inductively coupled plasma mass spectrometer (ICP-MS), and sequential chemical extraction of elements. The results show that the intrusion of diabase have caused coals within the rock-coal contact metamorphic zone to have undergone varying degrees of thermally-altered metamorphism and even to have transformed into natural cokes. The random vitrinite reflectance (R_o,ran), ash (A_d) and sulfur (S_t,d) content of coal increase obviously, and volatile matter (V_daf) decrease significantly. Kaolinite is the main clay minerals in unaltered coals, while illite and chlorite are predominant clay minerals in thermally-altered coals and natural cokes, as well as quartz and vein-filled pyrite also occur in natural coke. It is significantly richer in major elements and toxic trace elements such as Cu, V, Sr, Ba, Cs, Rb, U and Hg in the natural coke and thermally-altered coal than in unaltered coal. Coal-diabase contact alteration results in changes in the modes of occurrence of trace elements such as Cr, Ni, Co, Sr and V, which are mainly organically bound in unaltered coal, but are mainly in aluminosilicate bound in thermally-altered coal and natural coke. This study reveals that diabase intrusion has a significant impact on the coal quality, mineral components and the distribution and mode of occurrence of toxic elements in low-sulfur coal, which can provide important reference data for the geochemical study of magmatic thermally-altered coal.