A strain B1 belonging to Pseudomonas aeruginosa with high petroleum-degrading efficiency was isolated from Dagang oil-field wastewater treatment plant. More than 80% petroleum-degrading efficiency was obtained at 32°C, 200 r/min. According to the orthogonal test, the environmental impact factors influencing petroleum-degrading efficiency of the strain were investigated. The optimum environmental conditions for petroleum degradation were as follows: temperature was 40 °C, pH 8.0, oil inoculation 1 mL, nitrogen content 0.05 g. And the biodegradation efficiency of the strain reached 86.1%.