Abstract: To study the influence of alkali metals on the microstructure of coke and the changing rules of melting loss reaction，the gasification experiment of coke was carried out by high-temperature thermogravimetric analyzer and infrared metallurgical heating equipment，and the changes of microstructure and optical structures of the products were analyzed by X-ray diffractometer（XRD）and polarized microscope. The results show that with the increase of alkali metal solution concentration， the initial reaction temperature of coke decreases，and the layer spacing d002，the stacking height Lc， the microcrystal size La，the number of layers N，the number of aromatic rings n and the degree of graphitization r0 increase with the increase of alkali metal concentration and reaction time.

Key words: Melting loss reaction, XRD, Coke degradation, Alkali metals