The invention discloses a natural circulating steam injection boiler fed with high salt-containing softened water and a water circulating method, and belongs to the fields of natural circulating steam pocket water power technology and stage evaporation technology. A steam pocket is divided into a net section and a salt section, boiler feed water is directly introduced into a vertical down pipe ofthe net section of the steam pocket, and the evaporation heating surface of the net section is arranged on the heating surface of a hearth. The feed water of the salt section of the steam pocket is supplied by the boiler water of the net section, the evaporation heating surface of the salt section is arranged in a flue at the tail of the boiler, and the sewerage is directly led out by a steam-water separation device on the salt section of the boiler. The blow-down rate of the boiler is 5 to 15 percent, and the evaporation capacity of the salt section is 5 to 40 percent of the total evaporation capacity. Under the same blow-down rate, the boiler water of the net section and salt section heating surfaces of the boiler has low salt content; the heating surfaces have good corrosion resistance, hydrodynamic characteristic and safe heat transfer; and the heating surface of the salt section is convenient for overhauling. The fuel of the boiler can be coal, oil, natural gas and other combustible solids, and is suitable for high-capacity thick oil thermal recovery steam injection boilers.