Abstract: The fluxing mechanism of rice straw for Jincheng anthracite with high ash fusion temperatures was investigated under weak reducing atmosphere by CaO-Al₂O₃-SiO₂ ternary phase diagram, X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDX). The fusion temperatures of blended ash decrease, and the content of basic oxide CaO, Na₂O and K₂O increases with increment of rice straw addition. The slagging index R_b/a is between 0.20 and 0.69. The fluid temperature (FT) declines to 1 369℃ by adding 20% rice straw, which could satisfy requirement of liquid slag discharge for gasifier. The addition of rice straw reduces the initial temperature and increases the occurrences proportion and probability of liquid phase in the ash. The formation of crystal albite with low melting point and eutectics formed from anorthite, quartz and mullite lead the decrease of ash fusion temperatures.