The stress relaxation mechanism at the GeO2/Ge interface is studied by means of classical molecular simulation employing empirical force-fields. In general, the chemistry in GeO2 is characterized by weaker bonds and softer bond angles than that in SiO2, which has been considered to lead to the relaxation of the GeO2 film on Ge substrate. However, Ge-O-Ge angle is suffer than Si-O-Si angle, and has a narrower equilibrium angle of 133° than that of Si-O-Si of 144°. The present simulation results show that the narrow Ge-O-Ge bond contribute the reduction of the compressive stress in the GeO2 films. If the Ge-O-Ge bond angle had the same equilibrium angle with Si-O-Si angle, a higher residual stress would remain in the GeO2 films.