In the condition of potting planting in greenhouse, the effects of foliar spraying exogenous melatonin (MT，100 μmol·L^-1) on the growth, physiological and biochemical characteristics of Dendranthema morifolium ‘Jinyu Chuju’ seedlings under moderate drought stress(40% of soil field capacity), to explore the new pathway to improve the drought resistance of D. morifolium. The results showed that: (1) the drought stress could decrease the chlorophyll content, net photosynthetic rate and water use efficiency, increase the contents of soluble protein, soluble sugar and proline, but obviously increase MDA content and relative conductivity, and significantly inhibit the growth of D. morifolium ‘Chuju’ seedlings. (2) Exogenous MT could significantly alleviate the cell membrane damage by improving the proline, soluble protein and soluble sugar contents, perform the lower contents of relative conductivity and MDA, and keep the higher chlorophyll content and net photosynthetic rate, in the leave of D. morifolium ‘Chuju’ seedlings under drought stress. (3) Comparing with the drought stress treatment, the shoot fresh weight, root fresh weight, shoot dry weight and root dry weight of exogenous MT treatment were all significantly increased. The study found that exogenous MT can effectively reduce the damage of drought stress on the cell membrane, maintain the normal function of leaf cell membrane, and keep the higher net photosynthetic rate and water use efficiency, by promoting osmotic adjustment substances, and thereby improve the adaptability of D. morifolium ‘Chuju’ seedlings under drought stress.