In this paper, a 3D model was constructed for a type of spiral flow mixer with immovable parts, using turbulence model, unsteady model and heat transfer model to simulate the internal state of the mixer on computational fluid dynamics theory. Through the analysis of the path line, the change rule of temperature and so on, the paper discussed the characteristics of flow and heat transfer in the mixer and the change rule of export temperatures with inlet velocity and mixer''s volume. The calculation results showed that spiral flow mixer can get better mixed effect; the relation between mixed effect and inlet velocity was direct ratio; mixed effects obviously change with the change of mixer''s volume, and along with the increase of volume, the regulatory time significantly increased.