| 【Objective】In this study, uniconazole was used to soak the sugarcane seeds. The optimum concentration of uniconazole that can promote the early occurrence of sugarcane tillering and high tillering rate was proposed to increase the effective stem number and yield per unit area of sugarcane.【Method】The conventional sugarcane seed of Guitang 42 was used in this experiment and four treatment concentrations were set, including 0 mg/L, 20 mg/L, 40 mg/L, and 60 mg/L, to soak the seeds for 2 h.【Result】The results showed that the SPAD values of newly planted sugarcane treated with 20 mg/L,40 mg/L, and 60 mg/L uniconazole increased by 20.5%, 21.1%, and 27.2%, respectively, compared with that of 0 mg/L, showing extremely significant differences; and the tillering rate of 20 mg/L, 40 mg/L and 60 mg/L treatments increased by 48.96%, 119.74% and 169.90%, respectively, compared with that of 0 mg/L treatment, with extremely significant differences. Among the 4 treatments, the effective stem number and yield of 20 mg/L uniconazole treatment were the highest; among them, the effective stem and yield of newly planted sugarcane were 59 640 pieces/hm2 and 102.22 t/hm2, respectively, which were 8.32% and 8.48% higher than those of CK. The effective stem and yield of ratoon sugarcane were 72 894 pieces/hm2 and 105.56 t/hm2, which were 12.45% and 16.05% higher than those of CK, respectively. The sucrose contents of newly planted and ratoon sugarcanes did not change with the increase of uniconazole concentration. 【Conclusion】Soaking seeds with 20 mg/L uniconazole can effectively increase the SPAD value of +1 leaf in seedling stage of the newly planted sugarcane, the tillering rate, effective stem number and yield per unit area, and the stooling capacity and yield of ratoon sugarcane, indicateing that the concentration of uniconazole should not be too high.