The present application provides a use of a hyaluronic acid or a salt thereof and/or trehalose in stabilizing ergothioneine, an additive for stabilizing ergothioneine, the additive containing the hyaluronic acid or the salt thereof and/or trehalose, and a composition, the composition containing ergothioneine, the hyaluronic acid or the salt thereof, and trehalose. Compared with other auxiliary materials, the hyaluronic acid or the salt thereof and trehalose provided by the present invention can obviously mitigate the damageof a high temperature to ergothioneine, thereby increasing the yield of an ergothioneine powder product. The composition obtained by the present invention has good antioxidant and anti-apoptotic effects. Moreover, the inhibitory and scavenging effects of a composition obtained by compounding the hyaluronic acid or the salt thereof and trehalose to be used as an auxiliary material on intracellular reactive oxygen speciesare obviously better than those of a composition obtained by using a single hyaluronic acid or a salt thereofor trehalose as an auxiliary material.