The low pressure desalting reverse osmosis membrane element is a polyamide composite membrane used for surface water and groundwater, which has the characteristics of low pressure operation, high water yield and good desalting performance. It can achieve the same high water flux and high desalination rate as conventional low-pressure membrane under lower operating pressure, and its operating pressure is about 23 of the conventional low-pressure composite membrane operating pressure, and the desalination rate can reach 99.5%, which can be used for the treatment of surface water, groundwater and municipal tap water with salt content below 2000ppm, of which 8 inches are mainly used in large and medium-sized chemical, pharmaceutical and food products Power plants, electronics plants for the process of pure water, boiler supply water, etc., can also be used for municipal water desalination and purification treatment. The 4-inch membrane is mainly used in small-scale pure water and ultra-pur