With the development of the city, the water quality of many rivers in the city becomes worse, thus improving the water quality of the river is very necessary. This main causes of water quality deterioration in a city river are analyzed, such as non-point source pollution, rural domestic sewage and river sediment pollution, and a series of technical measures are put forward to improve water quality, including water environment improvement measures, water ecological restoration measures, basement restoration measures, construction of constructed wetlands, etc. The research shows that the above measures can reduce the inflow pollutants and enhance the self-purification ability and ornamental function of aquatic plants. On this basis, the water environment can be steadily improved for a long time, and the annual average water quality of the section can reach the water quality target of Class III in the "Surface Water Environmental Quality Standard".