Abstract: The in-orbit environment for space remote sensor is much more different from that in the ground; the deformation of the composite materials which is affected by the moisture desorption will result in the imaging quality of space remote sensor. The methods of measurement for the dimensional stability of the composite materials must be studied specially. A method which was using the principle of laser interference for measuring the deformation of the composite materials when subjected to the in-orbit thermal-vacuum environmental conditions was proposed. The method was verified and the precision was analyzed. It indicates that the method has higher precision than others. A experience which was based on the carbon fiber/aluminous honeycomb core composite materials was done to analyze the dimensional stability of the composite materials. The results show that the experimental data and theoretical data are the same in order of magnitude. The method is feasible and can be used in testing the dimensional stability of composite materials.