The invention relates to a protection method for improving the salt expansion or the dissolution sink of salty soil, which is characterized in that calcium carbide ash, fly ash, zeolite and salty soil are adopted, are mixed and stirred according to the volume ratio of 1:1:1:9 and are used for the filler improvement of a road embankment, broken stone and gravel are adopted as a buffer layer, bitumen, geomembranes and geotextiles are adopted as a partition layer, a geogrid reinforcement improved filler is adopted, a sack filled with greening grass seeds, shrub seeds and improved soil is adopted to press the toe of a slope, and a side slope adopts the protection of the companion planting of grass and shrub and the combination of a hanging net. The invention has the following advantages of: (1) adjusting measures to local conditions, making full use of the salty soil, saving resources, utilizing wastes, such as the fly ash and the like, and realizing the utilization of the wastes; (2) adopting a structural protection system formed by the improved salty soil and a geogrid together and solving the problems of stability and uniform settlement of a fill slope; and (3) combining the grass and the shrub, reaching the ecological requirement on one hand, solidifying a sloping surface on the other hand and preventing the water and soil loss and the salt expansion or the dissolution sink. The invention is suitable for the problem of engineering improvement of the salty soil in civil engineering and can be used for the engineering of the filling of a highway embankment, the protection of the side slope, the construction of a foundation, the improvement treatment of a foundation pit and the like.