The invention provides an improver and a detecting method for salty soil in high severe cold areas. The improver is composed of coal ash, carbide slag, steel slag, superfine slag powder and a TG-2 soil consolidator. The ratio of the improver is determined according to the different contents and types of salty soil in different areas, the salty soil is subjected to improvement experiment, the frost heave and thaw collapsibility effect of the improved salty soil are detected by using a multiple freezing and thawing circle detecting device, meanwhile, an improved salty soil test piece is prepared by using a test piece preparation device, mechanical parameters such as strength and the like of the improved salty soil are detected by using a triaxial shear apparatus to obtain technical parameters required by engineering construction, and then, the improved salty soil is comprehensively judged. The improver has important scientific value and practical significance.