Dynamic mechanical relaxations of La-based metallic glasses were investigated by mechanical spectrosco-py.In the framework of the mixing enthalpy of constituent atoms, it was found thatβrelaxation was less evident by the addition of Cu to replace Ni in the LaCuNiAl glassy alloy.By introducing Cu into the LaNiAl metallic glass, the mixing enthalpy was less negative, which led to weakerβrelaxation of the me-tallic glasses.Theαrelaxation of the La-based metallic glasses could be described by a Kohlrausch-Wil-liams-Watts (KWW) function with a Kohlrausch exponentβKWW around 0.5.It should be noted that physical aging above the glass transition temperature Tg induced a decrease ofβrelaxation intensity in the La-based metallic glass.