Abstract：By processing the observation data of 50 mobile geomagnetic vector survey points in Shandong and its surrounding areas from 2018 to 2020, we obtain the variation characteristics of lithospheric magnetic field in two consecutive periods from April 2018 to April 2019 and April 2019 to April 2020. The results show that the horizontal and vertical vectors in the two periods have obvious local anomaly characteristics near the epicenter of Changqing M4.1 earthquake; the anomaly may appear nearly 2 a before the earthquake. The amplitude of horizontal vector near the epicenter of the previous period is relatively high, the direction turns in the near field and is relatively consistent, the amplitude of vertical vector is also high, and reversal occurs near the epicenter. In the later stage, the horizontal vector direction near the epicenter converges and the energy weakens, the amplitude of the vertical vector is also low, and the direction is reversed near the epicenter. The abnormal energy is first strong and then weak, which may be related to the phased change of stress state in the earthquake area.
