A new method of drying early harvested wheat grains having high moisture content has been developed: classification drying based on moisture content using a thickness grader. Grain size is known to be roughly proportional to moisture content. We therefore clarified the relation between grain thickness and moisture content before the drying process, and demonstrated the possibility of new classification drying. Based on the results, we found that a 3.2-mm sieve was optimal for a roughly uniform separation of grains having moisture content of around 35%. For the drying process, the thicker grain group had higher moisture content and its flour was vulnerable to discoloration and degraded starch quality. Moreover, we found that it is important leave grains of high moisture content—the thicker grain group in classification drying—exposed to airflow in order to prevent degraded quality. Practical experiments conducted with a circulating batch dryer showed that the thinner grain group having lower moisture needs less time for drying due to the lower initial moisture content.