This study was conducted to investigate the alleviating effect of exogenous hydrogen sulfide on chestnut seedlings under salt stress. The effects of different concentrations of (0, 0.1, 0.2, 0.5, 1.0 and 2.0 mmol/L) sodium hydrosulfide (NariS) on the photosynthesis of 'Hongli 2' chestnut seedlings and the chlorophyll content, proline content and malondialdehyde (MDA) content in chestnut leaves under 100 mM NaCI stress were investigated. According to the results, spraying exogenous NariS had positive effects on photosynthesis of chestnut leaves. The application of NariS could alleviate the damage caused by salt stress on the leaves of chestnut seedlings to different degrees. Compared with the sole treatment with 100 mmol/L NaCI, the chlorophyll content and the proline content were improved. Moreover, MDA content had a significant drop, which effectively reduced the damage of cell membrane under salt stress, The alleviating effect was not obvious with the in- crease of treatment concentration, and the 0.5 and 1.0 mmol/L NariS treatments exhibited better effects.