Aiming at the problems of high impurity rate and high loss rate of oil sunflower seeds in oil sunflower threshing production, a cut-flow oil sunflower threshing and screening machine was designed. The dynamic model of the vibrating screen was established by using RecurDyn software, and the motion law of the screen surface was analyzed with the center of mass point of the screen surface as the object. The results showed that the movement of the vibrating screen was conducive to forward transportation and dispersion of oil sunflower seeds, and it can effectively avoid the phenomenon of accumulation and clogging. The value range of drum speed, feeding amount, and preset threshing gap were determined through single factor test. Taking drum speed, feeding amount, and preset threshing gap as test factors, oil sunflower seeds impurity rate and loss rate were evaluation indicators, the Box-Behnken test was designed, and the Design-Expert 10.0.7 software was used to analyze the variance of the Box-Behnken test results, and a regression model of evaluation indicators and test factors was established. In order to reduce the impurity rate and loss rate of oil sunflower seeds, multi-objective optimization of the drum speed, feeding amount, and preset threshing gap was carried out, and a better combination of working parameters was obtained as follows: drum speed was 264r/min, feeding amount was 1.9kg/s, and the preset threshing gap was 36mm. The results of the threshing test showed that the impurity rate and loss rate of oil sunflower seeds were 1.94% and 2.64%, respectively, which met the requirements of threshing.