Hydrogen sulfide(H₂S) has been known as a new gasotransmitter which plays a vital role in regulating plant growth and responding to stresses.For deepening the understanding of physiological mechanism on the response to chilling stress in Chinese Cabbage (Brassica rapa var.pekinensis),we analyzed the influence of the seedlings growth conditions,photosynthesis and related genes expression levels under chilling stress which pretreated with exogenous H₂S (5 μmol·L^-1 NaHS treated 24 h).The results showed that:(1)The chilling stress activated the endogenous production of H₂S,and up-regulated the expression of the cysteine desulfhydrases coding genes,LCD,DCD and DES,which were identified as the main genes for endogenous H₂S emission.These data implied the close correlation among them.(2)The cabbage seedlings pretreated with H₂S showed obvious advantages in the aerial part height,the leaf width and the relative water content under chilling stress.The proline,the soluble sugar content and the photosynthetic pigment were increased significantly,along with the great improvement of the photosynthetic rate.And,the coding genes of some light-harvesting protein,ferredoxin,thioredoxin were up-regulated dramatically after pretreated with H₂S.From all these results,it could be concluded that physiological concentrations of H₂S could raise the photosynthesis through up-regulating the photosynthesis related-genes and P_n,promote osmotic adjustment and relieve the damage caused by chilling that could maintain the growth of cabbages under chilling stress.