MM5 that is developed by NCAR and PSU is one of the most widely used mesoscale weather forecasting model,and the MM5 benchmark is becoming one of the representative applications to measure the performance of computers applied in the meteorology field because of its typical algorithm and popularity.This paper studies the parallel computing algorithm of MM5.According to the characteristics of the Intel Itanium2 CPU architecture,based on a computing performance analysis,the MM5 parallel computational efficiency is optimized from the aspect of compiler options,code tuning,partitioning methods and processor topologies.The optimization results indicate that  the MM5 implementation performance can be increased by 20% on a certain HPC platform based upon the Intel Itanium2 CPU.