High sensitivity of ammonia detection from different emission sources can provide certain reference for environmental management and medical diagnosis. However, current ammonia sensors have the disadvantages of weak absorption line of ammonia in the near infrared band, high cost of mid-infrared light source and generally large volume. A photoacoustic sensor based on broadband light source was proposed in this work. For this system, the selected working wavelength is around 2239 nm, where the line intensity of ammonia is 10^-20 cm/molecule, which can effectively avoid the interference of CO₂ and H₂O. The results show that, the resonance frequency of the photoacoustic cell is 1830 Hz, the linear fitting of the measured signals of ammonia with different concentrations can reach 0.98976 under the conditions of room temperature, one atmosphere pressure and optical power of 2.46 mW, indicating the good linear response characteristic of the system, and Allan variance analysis show that the optimal integration time of the system is 100 s. It is shown that the developed sensor can meet the detection requirements of ammonia from different emission sources, and has important reference for realizing high sensitivity detection of ammonia.