Abstract: Rice printing planter is one of the effective methods for precise and uniform sowing of rice seeds. Due to the influence of mechanical vibration, seeding paper speed, and rice seed transportation, several rice seeds would adhere to some glue points on the seeding paper, which affected the seeding quality. To address this issue, a seed rate detection method based on machine vision for printing planters was proposed in this paper. Firstly, the image information of the seeding paper was collected by a CCD camera. Then, the red-green color difference was used to extract the seed color information, morphological processing methods such as Otsu threshold segmentation were used to separate the seeds from the background, and an opening operation was utilized to separate slightly sticky rice seeds. Additionally, the area threshold method was adopted to remove noise and accurately determine the number of rice seeds. Finally, the ratio between the total area of tightly adhered rice seeds and the average area of each rice seed was used to correct the number of rice seeds. The results show that the seed rate detection method is effective in obtaining the number of rice seeds from the glue point of the seeding paper. The range of seeds rate detected was 88.84%-92.05%.