The high-yield and high-quality japonica rice variety Nangeng 5718 and the middle-yield and high-quality japonica rice variety Changnonggeng 10 were used as the test materials to compare and study the differences in tillering occurrence and panicle formation characteristics of different genotypes, and to clarify the dominant leaf position of the high-yield genotype varieties. The results showed that there were significant differences between the high-yield genotype and the middle-yield genotype in tillering occurrence and panicle formation characteristics. Compared with the middle-yield genotype, the high-yield genotype had higher primary and secondary tillering rates and panicle formation rates, more panicles per plant and group, and better photosynthetic characteristics of each tiller position after flowering, which promoted the enrichment of storage capacity and higher final yield. The yield of Nangeng 5718 was 7.7% higher than that of Changnonggeng 10, more effective panicles were the important basis for its yield advantage. Compared with Changnonggeng 10, the number of panicles of Nangeng 5718 was lower at jointing stage, but higher at heading stage and maturity stage. The occurrence of tiller in Nangeng 5718 and Changnonggeng 10 was more consistent with the dominant leaf position of panicle formation. The primary tiller was mainly 4/0, 5/0 and 6/0, and the secondary tiller is 1/4 and 1/5 was the main one. The number of panicles formed per plant, the number of panicles formed by the primary and secondary tillers in Nangeng 5718 were significantly higher than that of Changnonggeng 10. The contribution rates of different tiller positions to the number of panicles per plant and population yield were all in the following order: primary tiller >main stem>secondary tiller. The yield difference between Nangeng 5718 and Changnonggeng 10 was mainly reflected in the primary tiller and the secondary tiller. Compared with Changnonggeng 10, Nangeng 5718 had higher photosynthetic rate and chlorophyll content in flag leaves 30 days after heading, and the difference was mainly reflected in the first tiller and the second tiller. The photosynthetic rate and chlorophyll content of leaves were in the order of main stem>primary tiller>secondary tiller.