The invention relates to a conveying device with a grain seed grading screening function and belongs to the technical field of conveying equipment. The conveying device comprises a housing, wherein two ends of the housing are connected with a feed opening and a discharge opening correspondingly; a winnowing bin is arranged under the discharge opening; a blower is arranged in the position, close to the lower part of the discharge opening, on the side surface of the winnowing bin; a guide plate pointing to the air opening of the blower is arranged under the discharge opening; a hard impurity bin and a seed screening bin are sequentially arranged in the winnowing bin, and the horizontal distance between the hard impurity bin and the blower is shorter than that between the seed screening bin and the blower; the bottom of the seed screening bin communicates with an exhaust pipeline; and the exhaust pipeline is connected with an exhaust fan on the outer side of the winnowing bin. According to the technical scheme, owing to the designs of the hard impurity bin and the seed screening bin, gravel particles, with heavy weights and large sizes, mixed with seeds can be separated from the seeds, so that preliminary separation and impurity removal of the grain seeds can be realized; and owing to the design of the exhaust pipeline, air in the winnowing bin can be guided to flow to the bottom of the seed screening bin, so that the seed grading screening efficiency is improved.