Abstract: The material of this study is ‘Summer black’ grape, only remained the tip of the grape floral clusters 3 cm, 4 cm, 5 cm and 7 cm, and cut off the other parts 7 days before the florescence, and used the clusters without cutting as the control.The grape floral clusters treated by 50 mg/L GA3 on full-bloom stage and they were divided into 3 teams and respectively used 50 mg/L GA3, 50 mg/L GA3 + 2.5 mg/L CPPU, 50 mg/L GA3 + 5 mg/L CPPU 15 days after full-bloom stage. The aim was to study the effects of different lengths of floral cluster by pruning on fruit growth and qualities of summer black grape, and provide a scientific basis in grape production．Results showed that the treatments of 3 cm, 4 cm and 5cm all significantly increased the length and diameter of berry, the every berry weight and the total soluble solids content and they all significantly decreased the titratable acid content. It is recommended that the floral clusters which is pruned to 3 cm are treated by 50 mg/L GA3 on full-bloom stage and 50 mg/L GA3 + 2.5 mg/L CPPU 15 days after full-bloom stage in production.