The multidimensional simulation models of diesel engine and methamol-diesel engine about their have been established, and were validated by experimental results. The results show that if 15% methanol (M15)is used in diesel engine without any variation of engine structure, the ignition delay period becomes longer, the penetration length is shorter,the break-up capability boosts up and the sauter diameter of droplet decreases, which suggests that the methanol-diesel blends engine has better spray characteristics. Moreover, it shows that M15 has a better mixing with air, the concentration field is more uniform and the soot emission is much lower. In addition, for M15 methanol-diesel blends engine, the swirl ratio has great influence on the distribution of turbulent kinetic energy of the cylinder.