Abstract: Effect of Hypsizygus marmoreus discards in a peator vermiculite culture substrate on the growth of lettuce (CX012) was studied in a greenhouse. Five mixing ratios of the composite substrate were formulated for the seedling cultivation. The results showed that, when a 3:1 volumetric ratio of mushroom discards and vermiculite medium was used, the seedlings performed significantly superioron leaf size, plant height, stem girth, soluble sugars and chlorophyll contents. The effects were extremely significantly different from those of control.