The viscosity of Cu melt is obtained to be in the ranges from 2.418 to 3.039mPa.s under vacuum atmosphere (2Pa), from 2.907 to 3.425mPa.s under nitrogen gas atmosphere and from 3.352 to 4.015mPa.s under argon gas atmosphere. The activation energy is estimated to be 0.224, 0.162 and 0.150eV for the vacuum atmosphere (2 Pa), nitrogen gas atmosphere and argon gas atmosphere, respectively. The results reflect the essential structural change in the Cu melt by using different atmospheres.