The focus plane of a space remote-sensing camera will decenter and defocus

to some extent

under the condition of space environment

which is changeable and complicated. A focusing mechanism is described in which precision spherical guide ways and cam guide mechanism are employed in order to meet the requirement of image quality of a space remote-sensing camera. The principles of choosing the project of focusing mechanism are introduced. The composition and working principles of this focusing mechanism

the design idea of its motion transition and the technical measures to improve its safety and reliability are stated. The result of precision analysis is presented.