The present invention relates to a greenhouse substrate rice seedling raising method. The greenhouse substrate rice seedling raising method comprises greenhouse construction, substrate preparation, seed treatment, sowing, plate placement, seedling management and seedling lifting. A support-free steel frame combined greenhouse is used and a hanging micro-spray system is arranged in the greenhouse;a high-quality organic rice seedling raising substrate with fluffy texture, rich microbial content, good acid-base buffer performance, rich organic matter and appropriate amounts of N, P, K and mediumtrace elements is chosen; and substrate plate placement, water spraying, sowing and substrate covering are conducted on a seeder assembly line. The greenhouse substrate rice seedling raising method solves a problem of connection between seedling raising and mechanical transplanting, bred seedling blocks match requirements of a rice transplanter for the seedling blocks, so that the mechanical transplanting can be promoted in a large area; the whole process of mechanical seedling raising is labor-saving, time-saving, high-efficiency, low-cost, etc.; and the cultivated seedlings are uniform andtidy, strong, good in root system development and coiling, free of incomplete coiling, light in weight, easy to transport, and rapid in a slow seedling growing period after transplanting.