[Objective] The purpose was to study the optimum composition ratio of compound substrate with spent mushroom compound （SMC） and cattle manure com- post （CMC） for the seedling growth of tomato, cucumber and watermelon. [Method] With internationally best formula substrate （turf：vermiculite=2：1） used for CK, SMC and CMC were matched according to different proportions to get different substrate whose physical and chemical nutrient properties and their effects on the growth of tomato, cucumber and watermelon were studied by means of plug seeding technolo- gy. [Result] The results showed that the bulk density, porosity and the pH of the compound substrates are all in the ideal condition. However, CMC increased the EC value and the pH of the compound substrates. Compound substrates with high ratio of CMC are not suitable for seedlings. [Conclusion] Tomato and watermelon seedlings grew well in the compost substrate with SMC：CMC=3：1 with no river sand. And the cucumber seedlings grew well in the compost substrate with SMC：CMC=2：1 with 5% volume river sand.
