The stress of TiO2 and SiO2 thin films has been researched, including stress model, measurement method and experimental results for different preparation conditions. Based on the model of curvature of deformed substrate, the stress of the films deposited with and without ion assist as well as with different substrate temperature has been measured and some useful results for both single layers and multilayer system of TiO2 and SiO2 have been obtained. The effect of packing density of the layer on stress is found as follows: the film with lower packing density shows a tensile and that with high pacing density shows a compress stress. The accumulated stress in multilayer system even can be diminished to zero by adjusting the preparation parameters.