Use a very important tool called ICEM CFD integrated in ANSYS Workbench to mesh the model of toss device and then apply the software FLUENT to simulate numerically and analyze the velocity distribution and pressure distribution, based on the RNG k-epsilon model. Numerical simulation results showed that air flow field and pressure distribution of toss device were asymmetry. Maximum wind speed of fan exit was 42.8 m/s, which met the actual needs. In a word, the design of toss device was reasonable. But there was the existence of the secondary flow in toss cylinder, making some gas couldn’t flow smoothly, thus affecting delivery efficiency. Through analysis of the stress field in the blower, the results showed that static pressure of windward side blade increased from roots to ends and flow channels between fan blades in different positions showed different static pressure characteristics. The maximum static pressure of windward side blade was 878 pa, the minimum static pressure of lee side blade just passing the export of fan was -950 pa, the negative pressure meaning suction. The conclusions provided a reference for structural optimization and performance improvement of the toss device of Yellow Corn Forage Harvester.