A sediment-water-Vallisneria natans system was built within a simulating lake system, where phospholipid fatty acids ( PLFAs) method was used to determine the changes in sediment microbial community structures in the submerged plant V. natans at different growth stages. The results showed that during the growth of V. natans, the organic matter content decreased first and then increased. The concentrations of total phosphorus, organic phosphorus and inorganic phosphorus decreased by 8. 97%, 7. 81% and 10. 28%, respectively, during the growth period. The microbial activity and total phosphorus in sediments showed ex-tremely significantly negative correlation. In the early exuberant period, microbial activity in the experimental group was greater than the control group, while the decline in the microbial activity of the control group was slightly higher than the experimental group. Microbial community structure in the sediments of different periods showed significant differences. Bacteria were the main part of the total sediment microbes, accounting for 76% to 84% of the total microbial. As to bacterial distribution, gram-positive bacilli were predominant. The percentage of gram-positive bacteria and fungi increased with the growth of the V. natans.%模拟湖泊系统构建了“沉积物水苦草( Vallisneria natans)”系统，应用磷脂脂肪酸( PLFAs)法测定在沉水植物苦草不同生长时期沉积物表层微生物群落结构的变化，探讨沉水植物对沉积物中的微生物群落结构的影响.结果表明，从苦草生长初期到旺盛期再到衰亡期，沉积物中有机质含量先下降后上升；总磷、有机磷、无机磷分别下降了8.97%、7.81%、10.28%；沉积物微生物的活性与总磷呈极显著负相关，在苦草生长初期和旺盛期，实验组的沉积物微生物活性大于对照组，而在衰亡期对照组的沉积物微生物活性略高于实验组；不同时期沉积物中微生物群落结构发生了明显变化，组成结构差异显著，微生物组成中细菌占主要成分(占微生物总量的76%~84%)；细菌中革兰氏阳性菌占主要优势，且革兰氏阳性菌百分含量随苦草生长呈上升趋势，革兰氏阴性菌呈下降趋势；真菌的百分含量呈上升趋势.
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