A field experiment was conducted on onion plants, Giza 20 at Ibshway, Fayoum governorate, Egypt in winter season (2017-2018). Compost manure was applied in the main plots and nitrogen and Phosphors levels were applied in the sub plots to study the interaction effects on the biodiversity of spider, soil animals and the yield of onion. Spiders and soil animals were sampled using pitfall traps. Community composition of collected spiders was determined using the Shannon-Wiener and Simpson Indices of diversity. A total of 1080 spiders included 9 families, 22 genera, 22 species and 704 spiders included 8 families, 20 genera, and 20 species were collected in compost manure treatment and zero compost respectively. According to Simpson, Family Laycosidae recorded the highest number of spiders. Sorensen Quotient of Similarity between compost compared zero compost concluded that 80%, of similarity. A total of 8097 individuals in compost manure and 6506 individuals in Zero compost system were counted from 9 observations on onion plants from seedling to maturity by using pitfall trap. Statistical analysis for spider, soil fauna, yield and various parameters were discussed.