Abstract: By changing the shape and location of Venturi feeder and the shape of inlet section of cyclone separator, four structures for high temperature pipe expansion equipment of 6400kg/h based on optimization model were given and numerically simulated to derive temperature and gas-solid distribution in the modeled flow fields by using small slip model and ANSYS/FLOTRAN CFD.The results showed that the third optimization model structure was the best, and was better than the initial structure of the said expansion system of 6400 kg/h, it could serve as a guide in production.