A experiment was done to study the relation between biological factors and nutrients in soil in an artificial fruit-grass ecosystem. The result showed, except total P was negatively correlated with cellulose-decomposing bacterium,cellulolytic enzyme,polyphenol oxidase, the other nutrients were positively correlated with all biological factors, in addition, most of the nutrients were significantly or extremely significantly correlated with biological factors. After the pathway analysis was done between soil nutrients and biological factors, the conclusion was reached, the urease,silicate bacterium,cellulolytic enzyme werethe main biological factors of deposit of organic matter; invertase was the most important factor affecting the rapidly available nutrients of N, P, K; the catalase, polyphenol oxidase, cellulose-decomposing bacterium selectively affected the deposit of organic matter and the forming of the rapidly available nutrients of N, P, K.