Abstract: The process changes of flowering phase(the squaring stage, the early flowering stage, blooming stage, ending flowering) and the changes of photosynthetic characteristics, antioxidant enzymes, the flowering response of Lilium casa blanca were studied using the bulbs of L. casa blanca as pot experimental material under the coordination treatment of gibberellin (GA₃) and ethrel (CEPA).The results showed that, 1) It increased the plant height, thick stems, bud length and flower diameter,advanced the blooming stage and extended the days of blossom of L. casa blanca under the treatment of GA₃ and CEPA during the flowering phase. There were significantly positive correlation between GA₃ and plant height, stem diameter and bud length, while there were a significantly positive correlation between CEPA and stem diameter, bud length and flower diameter. GA₃ made a significant influence in earlier and middle flowering in L. casa blanca. However, CEPA made a significantly negative correlation with ending flowering; 2) The treatment of GA₃ and CEPA both advanced the photosynthetic pigment in leaves of L. casa blanca, and alleviated the downward trend of chlorophyll at the ending flowering time effectively, also it prolonged the photosynthesis time in leaves; 3) The treatment of GA₃ and CEPA both significantly promoted photosynthetic rate (P_n), conductance to H₂O (G_s), transpiration rate (T_r) and stomatal limitation value (L_s), But there were a significantly negative correlation between intercellular CO₂ concentration (C_i), transient energy utilization efficiency (LUE) and others. Analysis showed that, the treatment of GA₃ and CEPA enhanced the activity of leaf cells, increased the intensity of photosynthesis in leaf; 4) MDA content in leaves is lower than CK significantly under the treatment of GA₃ and CEPA during the flowering phase, and the activity of SOD and CAT increased. At the same time, the treatment of GA₃ and CEPA slowed down the downward trend of SOD activity in the middle and ending flowering time, relieved the ageing process of L. casa blanca, and it reached the purpose of extending the time of blossom of L. casa blanca. Comprehensive analysis shows that, the treatment of GA₃ and CEPA advanced the photosynthetic characteristics and antioxidant enzymes of L. casa blanca, It made a significant influence in the blossom quality and flowering phase. Among them, the coordination treatment GA₃ 200 mg/L+CEPA 30 mg/L is the best in regulation on advancing flowering time and extending the days of blossom in L. casa blanca, followed by the single treatment CEPA 60 mg/L and GA₃ 200 mg/L. However, the adjust action decreased in high concentrations coordination treatment GA₃ 200 mg/L+CEPA 60 mg/L and GA₃ 300 mg/L+CEPA 30 mg/L.