Aming at the dynamic pressure sensor calibration, the pressure can not be accurately traced, a method of measuring refractive index of water medium by laser interferometry was used for sinusoidal pressure calibration. The pressure chamber was filled with water medium and generated dynamic pressure. Taking the periodic sinusoidal pressure as an example, the dynamic pressure of the medium was obtained by measuring the change of refractive index of the water under the sinusoidal pressure by laser interference. In order to measure sinusoidal pressure accurately, a mathematical model was established and verified by experiments. A special demodulation system was developed to measure sinusoidal pressure accurately through hardware and software cooperation. Through static and dynamic experiments, the mathematical model of pressure measurement based on laser interferometry was validated. It is feasible to measure dynamic pressure by laser interferometry, and the value of dynamic pressure can be traced back to such basic quantities as time and length.