In order to study the feasibility of biodiesel applied on diesel engine, the performance test was conducted on a turbocharged in-line 6-cylinder common rail diesel engine. The results show that the viscosity, solidification point and distillation temperature of biodiesel/gasoline blended fuel decrease and the calorific value increases with the increase of gasoline blending ratio. At partial and medium loads, the peak combustion pressure, peak heat release rate and combustion temperature of biodiesel/gasoline blended fuel increase. The in-cylinder pressure, instantaneous heat release rate and combustion temperature of three fuels have little difference at high load. NOx emissions of BD90G10 and BD83G17 increase by 4.2% and 6.7% respectively and soot emission reduces significantly at 1400r/min compared with biodiesel. For ultrafine particles (D < 220 nm), the peak number concentration of mixed fuel corresponds to a smaller diameter than that of biodiesel. In addition, gasoline blending can effectively reduce the emission of ultrafine particles at low and medium loads, but the particle number concentrations of BD90G10 and BD83G17 blended fuel are almost the same at high load. Accordingly, the further increase of gasoline blending ratio has little effect on the emission reduction of ultrafine particles.