In order to make the high liquid limit soil used as filler in the upper embankment or road bed work area, this paper uses industrial solid waste (fly ash, steel slag, etc.) to prepare polymer and cement traditional improved materials to improve the high liquid limit soil, studies its mechanical properties and analyzes its economic benefits. The mechanical properties, stability and durability of high liquid limit soil improved by industrial solid waste polymer were studied through liquid-plastic limit test, indoor compaction test, shrinkage test, CBR test and dry and wet cycle test, and the improvement mechanism was analyzed. The effects of solid waste content, dry and wet cycle, compaction degree and other factors on the mechanical properties of high liquid limit soil were systematically analyzed. The results show that with the increase of solid waste content, the plastic index and liquid limit of high liquid limit soil decrease obviously, and the shrinkage coefficient decreases greatly. The CBR value of the improved soil with 96% compaction degree and 3% solid waste and the CBR value of the dry and wet cycling 15 times all meet the construction specification value of the embankment embankment, and only small cracks appear during the cycling period and do not run through the sample. In terms of economic benefits, the consumption of 3% cement and 4% solid waste filling in cement is 23.8% lower than that of cement, saving construction costs. The results show that the high liquid limit soil has good mechanical properties after the improvement of solid waste polymer, and can be used as the filling material of embankment and road bed.