Aiming at the analysis of the principle of corneal pressure detection, a method for calibrating intraocular pressure during corneal pressure measurement with non-contact tonometer is presented, an experimental system has been set up and a prototype of the principle has been developed. By recording the data of photosensitive sensor and air pressure sensor, the optimum algorithm of corneal barometric center of gravity based on optimal envelope factor was used to extract the values of pressure sensor at barometric moment, and the optimal polynomial interpolation fitting method based on least squares was used to calibrate intraocular pressure. Simulated eye experiments showed that when the optimal envelope factor is 0.7, the instantaneous variance was the smallest (0.068); 5-order polynomial interpolation fit between in-cylinder pressure and intraocular pressure has the largest correction (0.997 1) and the smallest root mean square error (0.525 3). Conclusion： Experiments were carried out to verify the IOP measurement in human eyes. Compared with gold standard measurements, the measurement deviation is within ±1 mmHg. It shows that this calibration of IOP measurement is effective and feasible, and can help to diagnose eye diseases accurately.