Many testing methods are used to evaluate the volume stability of steel slag sand, but none of them can legalized widely, which hinders its extensive use. Three typical methods-chemical analysis method, steam powdering ratio and mortar bar linear expansion rate under hot-water curing condition are compared in this investigation. The results showed that though chemical analysis method could rapidly judge the volume stability, the content of free CaO and MgO wasn’t precise because of the interference of calcium hydroxide and magnesium hydroxide in aging steel slag sand; the maximum powdering ratio reflected the uneven distribution of expansion components ; mortar bar expansion rate visually presented the volume stability of steel slag sand when used in mortar or concrete. So it was a synthetic application in order to decide the volume stability of steel slag sand.