Abstract: The seedling experiment was conducted to study the effects of water control treatment with 100%, 80%, 60% and 40% substrate maximum water holding capacity on the growth and photosynthetic characteristics of pepper seedlings. The results showed that with the increase of water control degree（100% to 40%）, the plant height showed a downward trend, and the stem diameter, shoot dry weight, root dry weight, plant dry weight, seedling index leaf area per plant, leaf SPAD value, net photosynthetic rate, stomatal conductance, transpiration rate, maximum photochemical efficiency, actual photochemical efficiency and photochemical quenching showed a trend of increasing first and then decreasing, and the intercellular CO₂ concentration and non-photochemical quenching decreased first and then increased. Correlation analysis showed that the seedling index was significantly negatively correlated with intercellular CO₂ concentration and non-photochemical quenching, and was significantly positively correlated with all other indexes. In conclusion, moderate water control in seedling hardening can improve the photosynthetic characteristics of leaves to promote seedling growth, thereby increasing the seedling index and stress resistance of pepper, while excessive water control（40%） has an inhibitory effect. In general, 60% water control in seedling hardening is a suitable water management strategy for cultivating strong seedlings.