To ensure the high quality of data acquisition in high-precision ground magnetic surveys in the field, it is an important link to ascertain the instrument performance in a period using instrument calibration points. However, some workers fail to properly use instrument calibration points and thus fail to monitor the operation state of instruments on a day through the early and late calibration measurement of the instruments, affecting the acquisition of high-precision magnetic survey data. Based on the analysis of specific examples, this study proposed that the checking of early and late calibration measurement results of instruments should consider both the differences between these results, as well as the differences between these results and the actual magnetic field values of instrument correction points. The purpose is to ensure the high-quality field acquisition of high-precision magnetic survey data.