Abstract: In order to understand the component change of biogas slurry and guide the scientific fertilization, 39 biogas slurry samples were collected from marsh gas tanks at pig farms, cattle farms and households in Yangtze delta respectively, pH, organic carbon, COD, total nitrogen, NH₄-N, NO₃-N, organic nitrogen, total phosphorus, total potassium and heavy metals (Cu, Zn, Cr, Pb, As, Cd, Hg) were measured, the relationship among different components were analyzed by multivariate statistical analysis, the agricultural potential risk of heavy metal was analyzed. The results showed that the component (expect pH) of biogas slurry from different resources had significant difference, the amplitude of variation mainly belonged to medium and high strength. The content of phosphorus and heavy metal (Cu, Zn, As, Cr) was in the sequence of pig farms＞ cattle farms＞ households. The results of principal component analysis showed that the change of phosphorus, copper, zinc, arsenic and chromium in biogas slurry was similar, which might be related to the use of feed additives. Organic carbon and COD content were significantly related to the content of total nitrogen, NH₄-N and organic nitrogen, which might be related to the application amount and constituent of organic material in the process of ferment. Cadmium and lead had similar sources, which might be related to the local environment of marsh gas tanks. Nemerrow index was used to evaluate the agricultural potential risk of heavy metals of biogas slurry, the results showed that the irrigation risk of all biogas slurry with different sources belonged to no risk, but the application amount of biogas slurry produced from pig farms should be controlled.