Abstract: The peel derelict of hazardous substances from walnut fruit picking and processing has given a rise to the concern around the world. Walnut peel was used as the raw material and was left to mildew after its moist heat sterilization(temperature 121℃, 30 min)treatment, and then breeding strains were isolated from the walnut peel. The dominant species were to be gained through disproveal experiments, and adaptability of the species through detection changes in the main nutrient content of the peel around the mildew was researched . The results showed that the four walnut strains were isolated, which fall into Aspergillus flavus, Aspergillus niger, Penicillium and Trichoderma. Trichoderma strains is the most dominant strain among all the strains. The change of peel nutrients after mildew as follows ：soluble sugar content decreases by 6.03%, fat content decreases by2.97% ；proteins decreases by 7.68%, cellulose content decreases by 64.7%. In a conclusion, Trichoderma is adaptable to walnut peel and has decomposition effects, and can be developed as a new bio-fertilizers and biocides.

Key words: Walnut peel, Dominant strain, Trichoderma, Biological fungicide