Aiming at the problems of complex structure, large volume and difficult integration of multi-channel aerosol detection system for photoacoustic spectroscopy, a design of integrated modulation signal generation system capable of generating multi-channel parameter adjustable pulse-width modulation(PWM) wave is proposed. The system is based on STM32 processing and LabVIEW program. It realizes synchronous modulation of multi-channel photoacoustic spectroscopy by generating PWM signals with multi-channel frequency and adjustable amplitude. The specific indicators are the following. The amplitude, frequency and sweep frequency are continuously adjustable from 0 to 9 V, from 1 MHz to 72 MHz, from 550 Hz to 6000 Hz, respectively. Experiments show that the multi-channel photoacoustic spectroscopy system with tunable PWM wave integrated system is reliable, stable and easy to operate. The signal is consistent with that of commercial signal generator modulation, which proves the feasibility and reliability of the designed multi-channel modulator. The proposed design can provide reference for the integrated design of photoacoustic spectroscopy or other spectroscopy detection systems.