To improve the efficiency of mechanized rice planting in Xinjiang and screen for the optimal seeding rate for high-yield and high-quality cultivation under side-deep fertilization, a field experiment was conducted using the locally dominant variety Xinjingyi 9. Eight seeding rate gradients were established: 70 g/plate (T1), 90 g/plate (T2), 110 g/plate (T3), 130 g/plate (T4), 150 g/plate (T5), 170 g/plate (T6), 190 g/plate (T7), and 210 g/plate ( the local conventional seeding rate, CK). Indicators such as yield and its components, as well as rice quality, were measured, and principal component analysis (PCA) was employed to screen for the suitable seeding rate. The results indicated that with increasing seeding rates, effective panicle number, 1000-grain weight, grains per panicle, panicle length, and yield initially increased and then decreased. Treatment T4 (130 g/plate) achieved the highest yield by 14.92 t/hm², which was significantly higher than that of low seeding rate treatments (70-90 g/plate) and high seeding rate treatments (190-210 g/plate). As the seeding rate increased, amylose content rose significantly; however, there were no significant differences among treatments regarding milled rice rate, head rice rate, protein content, or taste value. Principal component analysis and membership function calculations revealed that the D-value ranged from 0.13 to 1.00, with T4 recording the highest value and CK the lowest. Integrating yield performance and rice quality, a seeding rate of 130 g/plate under side-deep fertilization is recommended to significantly boost rice yield and improve grain quality in Xinjiang.