Abstract: 12-year-old ‘Muscat Hamburg’ grape was used as a experimental material to study the enlargement effect of streptomycin on seedless berry and its residue in fruit. The results indicated that the rate of seedless was up to 96% if the clusters of flowers were soaked with mixture of GAs 50mg.L-1 and streptomycin 400 mg.L-1 before 3 days when the flowers is blooming fully. The residual amount of streptomycin in fruit at the tenth day after treatment decreased as 10% as that of beginning, and less than 1 mg.kg-1 when the fruit matured. Date analysis on the base of the gray system theory indicated that fruit was enlarged and its quality was improved when ‘Muscat Hamburg’ was soaked with CPPU 5 mg.L-1 and GAs 50 mg.L-1, GAs 100 mg.L-1 or GAs 50 mg.L-1 and CPPU 5 mg.L-1 2 weeks after full blooming fully.