Abstract: According to the type of DD calciner designed by my Institute for some program which its size based on experiences, the owners request us to check the design structure reasonableness now. In order to reduce the investment cost and shorten the test cycle, this paper adopts the numerical simulation technique to establish the 3D model and theory model which replaced the traditional test method. Through the simulation of internal flow field, we get the results such as the relevant pressure field, temperature field, particle flow and so on. All that will be used to prove the reasonable of the designed structure and find optimization of design scheme.