Abstract: Shenhua bituminous coal and corn stalks were selected as experimental materials, and the effects of biomass blending ratio on the ash melting characteristics and viscosity-temperature characteristics of Shenhua bituminous ash in a weakly reducing atmosphere were studied. The mineral composition and micro-morphology of ash were detectd by XRD and SEM, and the phase and mineral transformation of ash at different temperatures were simulated by thermodynamic software FactSage. The results indicate that with the increase in corn stalks addition, the contents of high melting point quartz, anorthite and cordierite in ash decrease, and the content of low melting point potassium feldspar increases. Besides, the critical viscosity temperature (t_cv), the lowest operation temperature (t_lp) of ash and the viscosity of slag reach to the minimum values as the blending ratio of corn stalk to Shenhua coal is 20%. When the temperature arrives at 1255 ℃, the value of viscosity is less than 25 Pa·s, which can meet the liquid slag discharging requirements of the gasifier. Combining the Urbain homogeneous model with the Einstein-Roscoe heterogeneous model and using the FactSage software to calculate the liquid phase content at different temperatures, an empirical formula for the viscosity prediction of the corn stalks and Shenhua bituminous coal mixed gasification slag has been obtained.