An experiment system to measure the spontaneous Rayleigh- Brillouin scattering line profiles of gas is designed in this paper. A narrow bandwidth laser delivers a vertical polarization beam of continuous wave light at 532 nm. The beam is focused on the pressure controlled gas cell, interacts with gas molecules and generates the scattering signal. The spontaneous rayleigh- brillouin (RB) scattering line profiles of gas are measured at the lateral direction of 90° of the cell. The spontaneous RB scattering line profiles of N2 under the temperature of 300 K and the pressure of 300 kPa are measured by this system. The results of experiment and simulation results of Tenti S6 model are compared and the causes of the deviation between them are analyzed. It provides a reference for future space lidar measurement of air parameters.