This study utilized Ruditapes philippinarum as the research subject to develop integrated grading and weighing equipment featuring drum screen grading coupled with automatic weighing to address the issues of low accuracy in grading and weighing R. philippinarum, as well as insufficient procedural coordination. Utilizing discrete element simulation , the grading and weighing processes of R. philippinarum were simulated and analyzed. The impact of roller screen rotational speed, roller screen tilt angle, and feed capacity on grading and weighing accuracies was investigated using response surface analysis in Design-Expert software. This study aimed to optimize the operational parameters of the complete equipment and validate its performance. The findings indicated that the primary factors affecting the accuracy of grading and weighing R. philippinarum, in descending order of influence, were the roller screen tilt angle, roller screen rotational speed, and the feed capacity. The device achieved a grading accuracy of 96.09% and a weighing accuracy of 98.79% under operational conditions of a roller screen rotational speed of 17 r/min, a roller screen tilt angle of 3°, and a feed capacity of 200 kg/h, . After completing the prototype manufacturing and operational validation, the grading accuracy was recorded at 96.56%, and the weighing accuracy at 98.16%. The results demonstrated that setting appropriate parameters for the roller screen tilt angle, roller screen rotational speed, and feed capacity could significantly enhance grading and weighing accuracies in the process of handling R. philippinarum. This research provides valuable insights for the design of post-harvest grading and weighing devices for shellfish.