Abstract: In the grain harvesting process, due to the different nature of the grain and the working condition of the harvesting machinery, the flow rate of the grain often fluctuates or is too large or too small, which can directly affect the harvesting efficiency and quality of the grain, and even lead to the failure of the harvesting machinery. Therefore, it is very important to control and regulate the grain flow accurately. This study designs a grain harvesting flow control system based on photoelectric alignment array, which detects the movement state of the harvester and the flow rate of the harvested material by using photoelectric alignment array, and then controls the speed and working state of the harvester to achieve accurate harvesting and control the flow rate of the grain. After experimental verification, the system has high accuracy and stability, can effectively control the flow of grain, improve harvesting efficiency and quality, and has a wide range of application prospects.