Abstract: In order to explore influence of physicochemical properties of mixed fuel on flow characteristics in nozzles of diesel engine, mixed multiphase flow model was used to simulate flow in nozzles of diesel engine with four different mixing ratios of biodiesel/n-amyl alcohol．Results showed that pressure, velocity and cavitation distribution characteristics of four fuels were basically the same．With increase of mixing ratio of n-amyl alcohol, speed of mixed fuel gas phase volume fraction in spray hole size the same cross-section were characterized by increasing trend, biodiesel mixed in certain proportion was n-amyl alcohol and biodiesel could significantly reduce density, viscosity and surface tension, improve fuel in liquidity, promote cavitation generation of fuel, and improve fuel atomization effect．