With the rapid progress of technology and manufacture, the number of telescopes in space is mounting dramatically. Considering launch cost, more and more engineers nowadays pursue lightweight and compact design of telescope in space. Traditional design scheme usually has a support plate for primary reflective mirror. It will take some space for other parts. The paper, taking a primary reflective mirror with 600mm in diameter as an example, put forward a novel design of circle support component instead of traditional support plate. It utilized a special structural layout to save more space. The paper specified this design scheme and made comparison between these two design schemes. The paper also gave the assembling method of the primary reflective mirror and circle support component, which would verify its feasibility in engineering practice in a virtual way. The novel structure design in this paper will give some guidance to engineers and designers, who are devoting themselves to designing space telescopes. © 2021 SPIE