Abstract: Using the‘New Wrinkled Pepper 5’pepper as the materials，the effects of the Ca2+ spray in different periods on pepper seedling agronomic traits and multiple physiological，biochemical indexes were studied in order to identify the better spraying period of mitigating the waterlogged stress. It is found that Ca2+ treatment can improve agronomic traits，increase antioxidant，respiratory enzymes activity，proline and total soluble sugar content，decrease relative conductively ratio，LDH activity，the accumulation of MDA and ?OH. There are significant differences when spraying Ca2+ in different period. When spraying Ca2+ before the stress day（before one and two days），the chlorophyll content，CAT，POD，SOD，GR，ADH，SDH，MDH activity and total soluble sugar is the highest，but the relative conductively ratio，LDH activity，?OH and MDA content is the lowest，and agronomic traits are significantly better；When spraying Ca2+ on the stressed day，the proline content is the highest；When spraying after thestressed day（after one and two days），the agronomic traits，antioxidant enzyme system，respiratory-related activity were worse. The result shows that the Ca2+ spray can alleviate the damage to some extent caused by waterlogged stress and spraying Ca2+ before suffering waterlogged stress can lead to the best result.

Key words: pepper, waterlogging stress, Ca2+, spraying period