This paper describes the design and realization of a refocusing system for a earth observation space TDICCD camera based on the satellite with 2 m pan resolution and 8 m multispectral resolution on 644.6 km sun synchronous orbit. The 100 km swath and wider field of view is acquired by the 8 TDICCDs mechanical interleaving assembly on the focal plane. Firstly, the four mirror anastigmatic off-axis optical system of this earth observation space TDICCD camera and the advantage of opticl system is introduced. Secondly, the refocusing system as well as the technique of TDICCDs mechanical interleaving assemble focal plane of this space camera is discussed in detail. Finally, the refocusing accuracy of refocusing system is measured by open-loop method. Experimental results indicate that the refocusing accuracy is ±7.2 μm(3σ), which can satisfy the requirements of refocusing accuracy for the high resolution TDICCD earth observation camera.