Microbial respiration is considered to be one of the most sensitive factors in soil; however, it might be altered by soil pollution. To clarify the potential impact of low levels of total petroleum hydrocarbons (TPHs) on soil microbial respiration (SMR) in tidal wetland in Jiuduansha, Shanghai, the distribution and characteristics of TPHs in the typical zones of the Jiuduansha Wetland and nearby watershed were analyzed, and the relationship between soil microbial respiration and TPH was studied. The results showed that the average concentration of TPHs in the soil was 23.98 mg·kg(-1), which was a relatively low pollution level. Moreover, the concentration of TPHs in the soil changed significantly with tidal elevation. The main petroleum pollutants in the soil were alkane and aromatic hydrocarbons with less than 10 carbons. The average concentration of TPHs of the surrounding watershed of Jiuduansha was about 0.26 mg·L(-1), indicating that it was grade III seawater. The concentration of the inner watershed was higher than that of the outer watershed, indicating that Jiuduansha wetland could enrich TPHs to some extent. Based on the results of regression analysis and a pot experiment, there was a relationship between TPHs and soil microbial respiration. The input of TPHs from the surrounding watershed over long term periods might improve the SMR of the Jiuduansha tidal wetland.