An optical design is proposed for the Michelson interferometer based line field-swept source optical coherence tomography (OCT) system. An aspheric lens group for beam shaping is utilized in the illumination system and a cylindrical lens group is used for the line focus of beams, thus the scanning dimension is reduced and the goal of high-speed imaging is realized. The shaping of Gaussian beam is obtained via adjustment of the parameters of the aspheric lens group. In the projection system, the telecentric structure can reduce the system errors, the combination of different materials can be selected to correct chromatic aberration in the near infrared wave band, and the design of two systems is completed. In the Zemax non-sequential mode, the illumination and projection channels are combined by a beam splitter and the ray tracing is done. The interference performance of this OCT system is confirmed. The results show that the designed OCT system can be used for the realization of high-speed and high-quality imaging.