NOVELTY - Process for mixing biodiesel with condensed coenocytic aroma resin carbon-based solid acid as catalyst comprises adding in grease, low carbon alcohol, and condensed coenocytic aroma resin carbon-based solid acid catalyst in three-necked container, heating with return flow and stirring; filtering material to get catalyst, separating the filtrate to obtain lower layer glycerine; adding in sodium bicarbonate (NaHCO 3) solution, washing until it is neutral; separating out organic phase by using separating funnel, drying organic phase, filtering; reducing pressure and distilling.    USE - The process is useful for mixing biodiesel (claimed).    ADVANTAGE - Process for mixing biodiesel with condensed coenocytic aroma resin carbon-based solid acid as catalyst has high reaction ratio, and the catalyst is cheap; few amount of catalyst is enough; the reaction condition is warm with short reaction time; the catalyst is able to be used repeatedly; it is environment friendly and has no other adverse effect, such as saponification; and the raw material cab be used directly without any process.    DETAILED DESCRIPTION - Process for mixing biodiesel with condensed coenocytic aroma resin carbon-based solid acid as catalyst comprises adding in grease, low carbon alcohol, and condensed coenocytic aroma resin carbon-based solid acid catalyst in three-necked container with electromagnetic stirring, heat indicator and loop condensing pipe and heating with return flow at 50-110 degrees C and stirring for 1-10 hours; filtering the material to get catalyst, separating the filtrate to obtain lower layer glycerine; adding in sodium bicarbonate (NaHCO 3) solution with 5-10% mass percentage into upper layer mixture, and it is added in by the weight 2-6 times of upper layer mixture, washing it until it is neutral; separating out organic phase by using separating funnel, drying organic phase with non-aqueous magnesium sulfate (MgSO 4), filtering to remove desiccant; reducing pressure and distilling to obtain light yellow crystal product which is biodiesel. Proportion of grease, low carbon alcohol and condensed coenocytic aroma resin carbon-based solid acid catalyst is 1:0.1-0.5:0.04-0.1. Grease is plant grease, animal fat or exhaust oil in production. Low carbon alcohol is carbinol, ethanol, ethyl or butanol.