Three rich-alkalis biomasses ashes, wheat straw ash (WSA), sea grape ash (SGA) and Ixeris Chinese ash (ICA) and calcium-based additives, were applied in char hydrogasification. Hydrogasification behavior of coal and biomass ash and saturated loading and loading methods of calcium-based additives were investigated. The loading calcium-based additives has affected on the methane release curves of SFC hydrogasification. The total amount of gaseous products and the CH4 yield were obviously improved with the increase of the CaO loading. Hydrogasification of SF char with the 6% calcium-based loading presented the highest methane yield. SFC hydrogasification was divided into two stages according to the methane release rate curve of the calcium-based additives-loaded samples hydrogasification. The carbon and hydrogen reaction occurred in the second stage of coal hydrogasification. The calcium-based additives have effects on catalytic performance of three rich-alkalis biomass ashes for hydrogasification characteristics of Shenfu coal char. Loading methods of calcium-based additives and component of biomass ashes affected on the total CH4 yield and the total amount of gaseous products of samples. Calcium-based additives emerged obviously synergistic reaction with WSA or SGA during char hydrogasification. Calcium-based additives reacted with Si of biomass ashes and produce more stable calcium silicate in the early stage of reaction. The promotion of biomass ashes on char hydrogasification mainly was attributed to the fixation of Si and Cl by CaO.