Abstract: In order to find the suitable sowing date and its high-yield growing characters, the effect of different sowing dates on the growing development and yield of koshihikari under the condition of cultivation after wheat in Huanghuai Area was researched. Two year’s field experiments were carried out with a randomized block design and three replications using the material of Koshihikari. There were four treatments of sowing date in 2013: T₁ (May 1st), T₂ (May 11th), T₃ (May 21st) and T₄ (May 31st), and the transplanting was on June 27th. The same treatments of sowing date were designed in 2014 and the transplanting was on June 30th. The result of 2013 showed that the difference of yield between T₃ and T₄ was not significant: T₃ was the highest: 6681.8 kg/hm² (sown on May 21st, 37 days of seedling age), T₄ was the second: 6533.2 kg/hm² (sown on May 31st, 27 days of seedling age). The result of 2014 showed that the difference of yield between T′₃ and T′₄ was not significant: the yield of T′₃ was the highest: 6866.4 kg/hm² (sown on May 21st, 40 days of seedling age). The second was T′₄: 6647.4 kg/hm² (sown on May 31st, 30 days of seedling age). By two years’ experiments, the composite agronomic-traits of sowing on May 21st were proved to be the best, that of sowing on May 31st were the second, showing concentrated tillering, low tiller position, high percentage of the first tillers, trim population growing, no early senility in the later-period growth, resisting to lodging, good color of maturity and high yield. The results showed that the suitable sowing date of koshihikari was in the late of May for summer rice after wheat in Huanghuai Area. Its whole growing period was 127 days and its available seedling age was about 35 days (6-7 leaves) and it matured on about Oct.1st. Delaying the sowing date appropriately was the key measure of avoiding early senility and lodging and increasing the yield.