In view of the phenomenon that the materials distribute unevenly on the sieve surface during the operation of 4LZ - 3.0Z rice combine harvester, with more materials on the sides and less in the middle, and more at the front and less at the back, which leads to insufficient screening of the materials during the cleaning process, a leaf-interlaced centrifugal cleaning fan was designed to generate a lateral airflow through the pressure difference between the front and rear vanes, improving the uniformity of the lateral distribution of the materials. A mathematical blade angle and wind speed model was established based on the pressure difference between the front and rear vanes during the fan's operation. By combining the theoretical pressure difference and the expression of the lateral wind, it was concluded that there was a nonlinear function relationship between the staggered blade angle and the lateral wind. Through numerical simulation of the fan flow field and the actual measurement of the wind speed on the sieve surface of the cleaning chamber, the rationality of the theoretical analysis was verified and the size of the lateral wind was obtained. Through single-factor experiments, it was determined that the deflector plate angle, fan speed and blade stagger angle were the influencing factors, and the grain impurity rate and cleaning loss rate were used as evaluation indicators to obtain the influence relationship of each factor. A three-factor three-level response surface experiment was designed. The optimal parameters were obtained through the response surface method and multi-objective optimization: the fan speed was 1 105. 614 r/min, the deflector plate angle was 39. 91°, and the blade stagger angle was 25. 073°. Under the optimal parameters, the grain impurity rate was 1. 08% and the cleaning loss rate was 0. 774%, which was superior to the performance of the traditional cleaning device.