Based on the characteristics of growth of plant organism, add organic additive made of the juice of alfalfas, wooden vinegar liquid, spring onions and juice, 4 kinds of plant ash and organic manure into the soil according to the growth stage, setting organic manure treatment as control. The result of this study shows: after treatment with this organic additive, the quantity of the soil microorganism increases markedly, meanwhile, the height &weight of tomato also have obvious changes, of which the changes of treatment group B is most obvious. Compared with control, the bacterium's quantity in the soil increases by 65.88%, 96.14%, 80.90% and 82.0% in 15d, 30d, 45d and 60d respectively; The quantity of soil antinomies increases by 16.01%, 54.01 %, 49.0%, and 49.8% respectively in the same time points. Accordingly, the average of height&weight of treatment group B increases by 35.22% and 34.97% respectively during the last period of seedling stage of the tomato. ANOVA analysis shows strong positive correlation between bacterium&actinomyces quantity and the height&weight of tomato seedling in various times of measurement.