In this article, advances in the study of the geomagnetic field over the last decade, especially changes in the Mesozoic geomagnetic field, are introduced. It is unveiled that during most of the Mesozoic (200~100 Ma) the paleointensity of the geomagnetic field was very low, only one-third of the mean Cenozoic value, that the geomagnetic field shows no reversals from 124 to 83 Ma, and that the true polar wander (TPW) almost remained a standstill from 170 to 110 Ma. Simultaneously, the earth surface is characterized by great unrest with many remarkable geological and geophysical processes, such as episodic mantle convection, plume activity, see-floor spreading, changes in global temperature and oil generation. The coincidence of these phenomena indicates some form of coupling among the core, mantle and earth surface activities. To comprehend the coupling, some schematic theoretical models which connect changes of the geomagnetic-field with the core-mantle boundary dynamics have been constructed in recent studies. Two main models are introduced and compared with each other. Finally, some valuable earth dynamics questions, which are the third challenge in the geoscience and need further research by geologists and geophysicists, are put forward in light of the latest progress in the study of Mesozoic geology of North China.