Electroplating was employed to prepare Cu films and Ni films on Ag substrates. The average internal stresses in Cu film and Ni film were measured in situ by cantilever beam test. The values of experimental internal stresses were compared with theoretical internal stresses. The results showed that the internal stresses of Cu film and Ni film decreased with the increase of the film thickness. The reduced gradient was faster. The values of experimental and theoretical internal stresses had the same variation trend with film thickness and the same characteristics (tensile stress). Theoretical calculation model of internal stress was of accuracy. The internal stress for the same substrate was in relation to the film material.