The requirement of infrasound calibration is increasing

but the traditional reciprocity calibration method is easily influenced by gas leakage in low frequency and its calibration result is not good. The new method called laser pistonphone calibration is more suitable for infrasonic microphone calibration.This paper designs a laser pistonphone calibration system based on virtual instrument.The system employs ultra-low frequency technology.The distortion of the piston displacement is very small. The SPL(sound pressure level)in the cavity is stable and large-scale.The software design of the system is flexible and convenient.After sound pressure feedback is introduced

a sound source with stable SPL can be achieved.