The structures of photoacoustic cavities are among the most important factors affecting the sensitivity of photoacoustic spectrum detection systems. Considering the emerging trend towards the miniaturization and portability of photoacoustic spectrum detection systems, this study considers a cylindrical photoacoustic resonator as its research subject. With a fixed total length of the photoacoustic cavity, finite element analysis of the photoacoustic resonator model is conducted to investigate the influence of the structural layout of the resonator and buffer chamber on the performance of the photoacoustic cavity. The results reveal that when the length of the resonator is constant, the maximum sound pressure signal intensity can be obtained when the two buffer chambers are symmetrically distributed. When the buffer chambers are symmetrical, and the total length of the photoacoustic chamber remains unchanged, the resonator quality factor Q increases with an increase in the length of the buffer chamber. The characteristic frequency first increases and subsequently decreases with the increase in the buffer chamber length and reaches a maximum of 2110 Hz at L_buff=70 mm. In the resonant state, the sound pressure signal reaches a maximum value of 5.61×10^-6 Pa at L_buff=40 mm.