Abstract: Through the observation and data analysis of Dimocarpus longan treatment group and control group with different flowerthinning methods, the effects of different flower-thinning methods on flowering, fruit setting and fruit quality were explored. The results showed that the number of flowers and fruit in the completely sparse group decreased significantly, and the fruit setting rate decreased, but the fruit quality was better. Some of the sparse flower groups retained the right amount of flower buds, the number of flowers was relatively large, the fruit setting rate was relatively high, and the yield and fruit quality were maintained. The delayed flower thinning group retained all buds and had the highest number of flowers, but the fruit setting rate was affected and the fruit quality was relatively poor. The research results can provide some reference and guidance for Dimocarpus longan growers, and provide theoretical basis and practical guidance for the improvement of Dimocarpus longan varieties and the development of cultivation technology.