Abstract: The tomatoes were selected as the experimental material, effect of treat with different concentrations of exogenous growth regulators on physiological reaction during the seedling. It was showed that the cold resistance was increased through the abscisic acid, salicylic acid, paclobutrazol, jasmonic acid, and the cold resistance was increased in higher concentrations. Conductivity in the seedlings was reducing significantly in 200ug/g ABA and 400mg/L salicylic acid. With growth of induced concentrations, proline and soluble proteoglycan were higher than in the control, but peroxydase was decreased. Following the 100 ug/g or 150 ug/g ABA, 300 mg/L salicylic acid, 60 mg/L paclobutrazol and 200 mg/L jasmonic acid treatment, the proline and soluble proteoglycan in seedlings increased to maximum, comparing to that in the control respectively. In addition, there are different effects of exogenous growth regulators on varieties but enhance cold-resistance were appearance.