Abstract: The biodegradability of polyepoxysuccinic acid (PESA) under different conditions has been investigated by the shaking-bottle incubating test.The results indicate that the concentration of activated sludge is 2 g/L,and the concentration of PESA are 800 and 50 mg/L,the biodegradability ratio are 52.56%,90.53% respectively;while the concentration of activated sludge is 0.1 g/L,and the concentration of PESA are 500 and 50 mg/L,the biodegradability ratio are 71.32%,84.05%,respectively.Besides,some comparable experiments for biodegradability are done among PESA and other scale inhibitors.The test indicates that the ability of the biodegradability has crucial relations with the molecular structure of polymer.The speed of biodegrading and the ability of biodegrading rely on the molecular structure.