In view of the design requirements of the characteristic frequency of the photoacoustic cell in the photoacoustic spectroscopy gas detection system in specific occasions, the first eight acoustic modes are obtained by using the finite element analysis method and taking the first order cylindrical resonant photoacoustic cell as the research object. This paper simulates and analyzes the influence of the radius and length of the resonant cavity and buffer chamber on the characteristic frequency and photoacoustic signal strength of the photoacoustic cell. The simulation results show that when the radius of the resonant cavity is 3 mm, the length of the resonant cavity is 120 mm, and the radius and length of the buffer chamber are 14.7 mm and 60 mm respectively, which are the optimal dimensions for the characteristic frequency of the photoacoustic cell around 1 400 Hz.