The mantle plume hypothesis proposed by Morgan has been in controversy all the time in spite of the fact that it has greatly propelled the development of earth sciences. This paper makes a tentative discussion on the focus problems, probes into the possible causes for the deviation of the volcanic tracks from the present-day locus of the active volcanism and the unfixing of the hot spots, and proposes a new possible dynamic model for the generation and continual development of the mantle plume: the result of long-term action by extraterrestrial objects.