Based on the traditional HFCVD system, a new set of miniature HFCVD diamond film-deposition system with a swingabe substrate platform has been designed. Simulations of the substrate temperature field have been done respectively when the platform is still, rotating continuously, or swinging. The results suggest that when the swing angle is bigger than 100, uniform temperature field close to that achieved through continuous rotation can be got. So, in this paper, the crank-rocker mechanism has been used to produce a swingable substrate platform, which simplifies the traditional structure. And satisfactory temperature field can be achieved. It meets the requirements of the miniaturization design.