Abstract: A halophilous protein degradation bacteria A- 3 was isolated from the restaurant wastewater by salt tolerance test and fermentation test.In order to determine the optimum conditions for the degradation of the strain, Four influencing factors such as initial pH, dissolved oxygen, inoculum size and carbon source were selected do degradation inoculation experiments. Based on morphologic observation, biochemical characteristic and identification of 16 S rDNA, A-3 belonged to the genus of Serratia sp.A3.The results showed that: The strain Serratia sp.A3 optimum degradation environmental conditions was pH7.0, dissolved oxygen 180 r /min, 5% inoculum size, the Sucrose could promote the protein degradation of Serratia sp.A3.