Abstract: Effects of plant regulators on photosynthetic pigment content and enzyme activity in leaves of Lilium casa blanca (Lily) were studied using an orthogonal design [L₁₆(4⁴)] of 6-BA, GA₃, IBA, and bulb soaking time. Experimental data was analyzed by ANOVA and correlation analysis. In different periods,the contents of chlorophyll a, chlorophyll b, and chlorophyll a+b in leaves were significantly higher than those in the CK. During the whole growth period, these photosynthetic pigment contents were highest when GA₃ was 150 mg/L, IBA was 40 mg/L, 6-BA was 60 mg/L and soaking time was 40 min. They increased to maximum at the squaring stage or initial bloom stage, and then decreased slightly or strongly. The activity of superoxide dismutase (SOD), and of catalase (CAT) was enhanced. Both SOD and CAT stayed at a high level when GA₃ was 150 mg/L, IBA wais 40 mg/L, 6-BA was 60 mg/L and soaking time was 40 min. However, the content of maloaldehyde (MDA) in leaves was lower than that of the control, and the upward trend of MDA in leaves became less. The MDA content was lowest when the experimental condition was GA₃ 100-150 mg/L, IBA 40-60 mg/L, 6-BA 60 mg/L and soaking time was 40 min. Analyses showed that the best combination of plant regulators was GA₃ 150 mg/L, IBA 40 mg/L, and 6-BA 60 mg/L with a soaking time of 40 min.