Aiming at the problem of high density of rice planting and large amount of straw in the black soil rice area of Northeast China, the uneven straw spreading during the return process affects the subsequent soil preparation and rice transplanting. An active centrifugal rice straw spreading device installed on a combined harvester was designed. By establishing the kinematic model and theoretical analysis of the three processes of deflector guide straw dropping plate, the spreading plate centrifugal spreading straw, and straw spreading in the air, the key components such as the deflector unit and the centrifugal spreading unit were designed. EDEM discrete element was used to conduct a single-factor simulation test to clarify the influence of speed of spreading disc, the declination angle of fan blade, inclination angle of deflector and returning rate on the variation coefficient of lateral uniformity of the spreading, and further narrow down the range of paraments. Taking the variation coefficient of lateral uniformity and the spreading width as the test indicators, the Box-Behnken parameter optimization and verification test was carried out by using the active centrifugal spreading test bench, and the optimization results were verified in the field. At the same time, the results were compared with a guide straw spreading device. The bench test results showed that the variation coefficient of the lateral uniformity of the spreading was 16.98%, the spreading width was 4.56 m when the speed of the spreading disc was 255 r/min, the deflection angle of the spreading fan blade was 7°, the inclination angle of the deflector was 35°, and the straw returning rate was 3.5 kg/s. The error with the predicted value was less than5%, meeting the design requirements. Through the performance comparison experiment with the original diversion straw spreading device of a combined harvester, the variation coefficient of lateral uniformity was reduced by 16.74 %, and the spreading width was increased by 0.42 m, which concluds that the active centrifugal rice straw spreading device developed had better spreading effect.