The utility model relates to a grain drying device. The grain drying device comprises a feed hopper, a square drum and a discharge hopper, wherein the feed hopper is arranged above the square drum, the discharge hopper is arranged at the lower end of the square drum; the grain drying device is characterized in that parallel hot air tube layers and moisture removal ventilating tube layers are staggered in the square drum, hot air tubes and moisture removal ventilating tubes are all oval tubes, through holes are formed in the side surfaces of the hot air tubes and the moisture removal ventilating tubes, one end of the hot air tube is sealed, the other end of the hot air tube is communicated with a hot air source outside the square drum, openings in two ends of the moisture removal ventilating tube are communicated with exterior of the square drum, and the discharge hopper at the lower end of the square drum is internally provided with a spiral auger. The grain drying device has the advantages that as the parallel hot air tubes and moisture removal ventilating tubes are staggered, the heat efficiency is greatly improved, the energy consumption is reduced, and the drying amount is improved by multiple times compared with the drying amount in the prior art.