The process of urbanization aggravates the endogenous pollution of urban lake sediment,and polluted sediment may seriously affect the quality of the water in lakes.At present,it is difficult to distinguish the difference between sediment that is heavily polluted by nitrogen (N) and phosphorus (P) when using an analysis based on a physicochemical index classification.The current study applied phospholipid fatty acid (PLFA) technology to further analyze the sediment characteristics from the perspective of microbiology.Surface sediment from five urban lakes that are heavily polluted with N and P in Wuhan were sampled.Statistical approaches were used to analyze the microbial community structure in the sampled sediment,and to determine the correlations between the microorganisms and physicochemical indices.The most severely polluted lake sediment had similar PLFA structures,the highest saturated fatty-acid content,and bacteria as the dominant microorganism.However,there were differences between the microbial biomass of the various sediment samples,which may have been related to the degree of N and P pollution.Analysis of the microbial diversity in the sediment samples indicated that the bacteria were experiencing starvation and nutrient pressure,which may have been due to the dissolved oxygen concentration of the heavily polluted lake sediment.A correlation analysis showed that the endogenous N and P had different effects on the microbes of the polluted sediment.A redundancy analysis (RDA) demonstrated that the N/P ratio had the greatest influence on the PLFA species,accounting for 83％ of thecumulative interpretation.To effectively promote the role of sediment microorganisms on circulating elements,it is necessary to regulate the N/P ratio of the sediment to some extent.When the N/P ratio in sediment exceeds 6,N pollution should be prioritized.