To reduce aberration, aspheric mirrors are usually used to fold the optical path in an optical system for a space remote sensor. In the optical detection of aspheric mirrors, the supporting structure is necessary for a compensator. On the basis of the definition of degree of freedom and coordination of the compensator, the degree of freedom required to adjust the compensator is analyzed by incorporating the position and function of the compensator in the detection optical path. According to the analysis result, the function and structure form which should be achieved for the compensator are confirmed. A supporting structure is designed and the analysis result of the adjusting precision of the supporting structure is given. The analysis result shows that the supporting structure has its displacement adjusting precision of 1.49 μm/deg and angle adjusting precision of 0.007 μrad/deg. The actual engineering application affirms that the supporting structure satisfies the requirements for use.