In order to reduce the manufacturing cost of optical gas concentration sensor, a meter-optical-path infrared gas absorption cell structure is designed and optimized by using ZEMAX optical design software. The structure consists of two parabolic mirrors for collimating and focusing light and five planar mirrors for increasing optical path. The simulation results show that the geometric loss of the gas absorption cell is only 1%, and the optical path is 1049.75mm. Compared with the gas absorption cell with traditional lens structure, the structure has the characteristics of small volume, long optical path, low loss rate and strong expansibility, and can be used to construct low cost and sub-ppm level infrared gas sensor.