Abstract: In order to promote the high yield,good quality and high efficiency cultivation of early maturing japonicarice in cold region,in this study,Longjing 31 and Longjing 39 were selected as test varieties,and quadratic orthogonal rotation combination were adopted to analyze the effects of fertilizer and density on their yield and quality.The results showed that the nitrogen application rate had a positive correlation with plant height and a negative correlation with 1000-seed weight,apositive correlation with spike length of Longjing 31,and the other characters had a conic relationship with the nitrogen application rate.Phosphate fertilizer had a certain effect on panicle length and panicle number per unit area.Potassium fertilizer had obvious promoting effects on panicle length,grain number per panicle and seed setting rate.Density had a great influence on the increase of panicle number per unit area.Appropriate reduction of nitrogen fertilizer could reduce the content of Longjing31 amylose,improve the percentage of refined rice and glue consistency,and reduce the chalky grain rate and chalkiness.Proper increase of potassium fertilizer could reduce the amylose content of Longjing 39,increase its polished rice rate and gum consistency,and reduce chalky grain rate and chalkiness.Through simulation optimization,and the regression model of fertilizer,density and rice population structure and rice quality,the best fattening plan of the two varieties was finally established.