A cylinder shape photoacoustic (PA) cell has been designed and fabricated for mid-infrared laser photoacoustic spectroscopy (MIR-PAS) gas sensing application. A complete modeling of the acoustic signal transmission and detection in the PA cell using FEM have been performed to simulate its characteristics and compared systemtically with the measured data. Results show that the second longitudinal mode of the PA cell has the highest resonance amplitude around 4.2 KHz with moderate Q value, so this mode is quite suitable for MIR-PAS gas sensing purpose.