Abstract: This study made acute (4 d) and chronic (29 d) experiments by setting different oil concentrations (WAF) and using Nitzschia closterium as the research object.We measured the effects of WAF on N.closterium by cell counting,malondialdehyde (MDA) measuring and the carbon/nitrogen stable isotopic analyses.The results show that WAF stimulated the growth of N.closterium in low concentration (1.0 mg/L),while the growth of N.closterium was restrained in relatively high concentrations (5.0 mg/L).The MDA content increased with the growth time and the increase of WAF concentration,up to the maximum of 1.65 times.The 13C and 15N value was higher in low concentration (1.0 mg/L),while lower in relatively high concentration (5.0 mg/L).Therefor the stable isotopic composition of microalgae may be used as an alternative method for oil pollution monitoring.