Abstract: New indica hybrid rice combination—Ⅱ Youfu 819 bred by pollen-radiation had the characteristics of good grain quality,high-yield,stable-yield and wide adaptability.The combination passed the examination and approval of the Crop Variety Approval Committee of Fujian and Jiangxi provinces respectively.In order to extend the combination,three influential elements including planting density(x1),seedling age(x2) and quantities of nitrogen(x3)applied,were studied by using optimized design.A regression model for these three elements and yield were established.The analysis result indicated that all of these elements affected the yield to some extend.According to the result of computer simulation screening,a comprehensive cultivating pattern was 148 000-281 000 hills per hm2,32-33 days for seedling age and 96.9-167.7 kg N applied per hm2.