In order to improve the water quality of Gaozhuang reservoir and improve its flood control and storage capacity, the reservoir ecological dredging project was implemented for Gaozhuang reservoir. This paper analysed the water quality monitoring data of the reservoir sediment by dredging. The results show that the water quality of Gaozhuang reservoir has a downward trend before dredging, and the grade of the section is mainly controlled by the factors of total phosphorus content, permanganate index and ammonia nitrogen content; the total nitrogen content in the sediment is mainly derived from dry matter, and the soil is not highly polluted,which is relatively clean; the heavy metals in the sediment have homology, indicating that their pollutional sources are the same; after dredging, the water quality grade of the reservoir is obviously improved, which can reduce the permanganate index and total phosphorus content in the water body, but the effect is not as obvious as reducing the ammonia nitrogen content; there are differences in the content of water pollution factors in different water seasons;the permanganate index in flood season is slightly higher than that in non-flood season, the ammonia nitrogen content in flood season is lower than that in nonflood season, and the total phosphorus content in flood season is higher than that in non-flood season. In order to improve the benefit of reservoir dredging, it is advisable to conduct another dredging after 10 years.