Research conclusions: By testing the silt content in interior hardened ballast and analyzing for frost heaving tests with different clay and water content，it states that the frost heaving rate is generally less than 4% when the silt content in ballast exceeds standard，and the frost heaving of ballast is the result of a combination of silt content and water content， so proof and drainage system must be good meanwhile effect of silt content on frost heaving should be paid attention to． The harmfulness of weak frost heaving behavior for ballast linear engineering treatment is greater than normal structures，and more attention should be paid．