Abstract: Often the excessive growth of Petunia takes place, which makes its quality reduced. The plug seedlings of Petunia are treated with daminozide (B9) and chlormequat (CCC) of different concentrations by foliage spraying. The result shows: the plug seedlings of Petunia are treated with B9, CCC and solution made up of B9 and CCC of different concentrations by spraying. Their effective and safe concentrations are 1000~2500 mg/L B9, 0.05%~0.3% CCC and 1500 mg/L B9＋0.3% CCC respectively. And their optimal concentrations are 2500 mg/L B9, 0.3% CCC and 1500 mg/L B9＋0.3% CCC respectively. Among the three optimal concentrations, effect of 1500 mg/L B9＋0.3%CCC is the best and that of 0.3% CCC takes second place. But the price of 2500 mg/L B9 is the lowest. When the concentration of CCC is beyond 1%, the phytotoxicity of CCC on the plants will happen.