Abstract: The cross flow blower has many advantages, such as a more uniform air flow distribution along its outlet axis. However, a complicated operational principle resulted in later application of the blowers in industries, especially in agricultural machines. In order to further understand its characteristics and probe into its structural and kinetic parameters and design one for combines in cleaning operations, a model blower was built and a series of tests were conducted. After performance tests and analysis, some practical data, such as the external blade tangent angle β₂ (15.33°), was obtained. Using the angle and similarity principle, a cross flow blower with parameters of external diameter of the impeller D₂=220 mm， inner diameter of the impeller D₁=154 mm, the number of impellers Z=20, inscribed angle of the impeller β₁=90°, circumscribed angle of the impeller β₂=15.33°, angle of inlet air angle of outlet air θ_j=170°, angle of outlet air θ_c=165°, angle of movable plate θ_s=25°, height of the air outlet h=130 mm, width of the air outlet B=1100 mm was designed. The blower used in a combine and running at a fixed speed (n=855 r/min) meets the cleaning load requirement in field operation. The tests indicate that the total loss rate, broken grain rate and clean grain rate are 1.09%, 0.05%, 98.15%, respectively.