The effects of night lighting on growth and morphology of cucumber seedlings in different stages were investigated with different light quality to improve seedling cultivation through photomorphologenesis, and the method of night lighting for cucumber seedlings were discussed. Cucumber seedlings were irradiated with 35μmol/(m2·s) red (R) or red and blue (RB) light from light emitting diodes (LED) for 2 hours in the night(19:00-21:00) at the temperature of 18~20℃. The effects of night lighting on growth, hypocotyls length, cotyledon area, stem diameter, leaf area, internodes length, dry weight, chlorophyll content and seedling index of cucumber seedlings at different stage were measured. Logistic curve was used to fitting the growth rate of leaf area. The cotyledon area and stem diameter were improved by 61.60% and 19.55% respectively compared to contrast at cotyledon stage, and leaf area and stem diameter were improved by 61.60% and 19.55% respectively compared to contrast at one leaf stage with R light night lighting. After three leaves stage, leaf area, stem diameter, dry weight, chlorophyll content and seedling index of cucumber seedlings with RB night lighting were improved by 41.92%, 17.75%, 45.45%, 21.92%, 200% compared to contrast, respectively. Night lighting could improve the growth and health index of cucumber seedlings. R light and RB light could improve the growth and health index of the earlier period (cotyledon stage and one leaf stage) and later period (after two leaves stage) cucumber seedlings, respectively. The method of using R light for early period and RB light for later period as night light could improve the quality of cucumber seedlings.