Abstract: 6-Benzylaminopurine at 25-100 ppm was applied to "Shuizhang" longan trees in late-November. Results showed that this practice has effects on the flower-bud differentiation in off-year. Flower cluster rate increased with the increase of 6-benzylaminopurine concentrations. The high concentration (100 ppm) has a significantly primotive effect on flowering (p≤0. 05). However, 6-benzylaminopurine had no obvious effect in on- year. All treatments have no unhealthy effect on the development of flower cluster, summer shoots and autumn shoots.