Optical pump magnetometers (OPMs), based on the SERF principle, are increasingly prevalent in biomagnetic field detection and localization studies. However, cross-axis crosstalk is an unavoidable consequence of the non-ideal factors introduced during the development of the sensor array, whether during the initial design or manufacturing process. This study introduce a novel method to compensate for cross-axis crosstalk by a set of three-axis coils.The gain matrix of each sensor in an OPM array is calibrated by the magnetic field generated by the activation of the three-axis coils. The results showed that the correlation coefficients between the corrected coil distribution field measurements and the true values improved substantially, exceeding 0.99. Similarly, the similarity between the forward-field simulation and the measured results for the localization of a physical model of a current dipole improved significantly, from 0.78 to 0.96. This work presents the first report of the simultaneous calibration of a large OPM array comprising 64 OPMs. The suppression of cross-axis crosstalk errors improves the sensor measurement accuracy and the consistency of the array. This method is expected to further improve the accuracy of OPM array-based source localization.