For the deviation between the actual wavelength and the output wavelength of the tunable wavelength infrared light source, an infrared wavelength calibrator based on photoacoustic spectroscopy technology was designed in this paper. Firstly, the gaseous small molecules are equipped in a photoacoustic cavity, with the tunable laser to be calibrated irradiated in the photoacoustic cavity, the vibration-rotational fine absorption spectrum of the molecule is obtained. Then, the known and accurate vibrational rotation spectrum peak positions of these simple gaseous molecules are compared with the obtained photoacoustic spectrum. Finally, the output light emitted by the infrared laser is corrected by the comparison. With this method, the existing infrared parametric oscillator (OPO/OPA,) in our laboratory has been calibrated in the range of 2800-3600 cm-1. Using a photoacoustic cavity containing gaseous methane and ammonia, the calibration fitting curve of the output wavelength of the OPO/OPA was obtained. This infrared light wavelength calibrator can be used in a wide infrared range. It is a complement to the existing laser wavelength calibrator.