In order to study the flow field distribution and variation law of the interaction between oil and screw in the chamber of a twin screw press, a physical model of the screw press and the fluid field was established. Fluent is used to solve the finite element simulation. The distributions of pressure field and velocity field and concentration field of oil in the press section were obtained. In the certain scope, the pressure and temperature were higher, and the concentration was higher, which was beneficial to get high oil yield.