Abstract: Gasoline/hydrogenated catalytic biodiesel（HCB） blends can alleviate the problems of low-load ignition difficulty and combustion instability in gasoline direct compression ignition combustion mode. Based on the principle of similarity of fuel composition and physicochemical properties, n-hexadecane was proposed as the surrogate fuel for HCB. Several methods were utilized to reduce the detailed mechanism of n-hexadecane（POLIMI＿1 412）and couple with the gasoline surrogate skeletal mechanism and nitrogen oxide sub-mechanism, and the final reduced mechanism containing 82 species and 370 reactions was obtained. Reaction pathway analysis and sensitivity analysis were carried out to optimize the reaction kinetic constants of several reactions. The results show that the sensitivity of each reaction for ignition delay time is varied significantly with temperature and equivalence ratio. Under low temperature conditions, most low-temperature reactions control the ignition, while for laminar flame velocity, small molecule reactions mainly play controlling role. By verifying ignition delay period, laminar flame velocity, component concentration and compression ignition engine, it is found that the simplified mechanism can well predict the autoignition and combustion characteristics of gasoline/hydrogenated catalytic biodiesel blends.