The activity of Mo2C-based catalyst on vegetable oil conversion into biofuel could be greatedly promoted by tuning the carbon content,while its modification mechanism on the surface properties remained elu-sive.Herein,the exposed active sites,the particle size and Lewis acid amount of Ni-Mo2C/MCM-41 cat-alysts were regulated by varying CH4 content in carbonization gas.The activity of Ni-Mo2C/MCM-41 catalysts in jatropha oil (JO) conversion showed a volcano-like trend over the catalysts with increasing CH4 content from 15％ to 50％ in the preparation process.The one prepared by 25％ CH4 content (Ni-Mo2C(25)/MCM-41) exhibited the outstanding catalytic performance with 83.9 wt％ biofuel yield and 95.2％ C15-C18 selectivity.Such a variation of activity was ascribed to the most exposed active sites,the smallest particle size,and the lowest Lewis acid amount from Ni0 on the Ni-Mo2C(25)/MCM-41 cata-lyst surface.Moreover,the Ni-Mo2C(25)/MCM-41 catalyst could also effectively catalyze the conversion of crude waste cooking oil (WCO) into green diesel.This study offers an effective strategy to improve cat-alytic performance of molybdenum carbide catalyst on vegetable oil conversion.