The dynamic mechanics of global plate tectonics,a hot topic in Earth Science,is a difficult and unsolved problem.This paper reviewed the main plate tectonics hypotheses of the last hundred years as well as critical new knowledges of the past forty years.Drawing inspiration from Rampino & Stothers' hypothesis of 1984,which relates periodic comet impacts to global change,the author proposed here a new plate tectonic dynamics hypothesis.As record shows,during the Mesozoic Cenozoic of the last 200 Ma,the solar system penetrated the Milky Way galactic plane every 33 Ma.The events greatly altered the gravitational field in the solar system,causing destabilization of some asteroids that could then impact the Earth.Based on the seven different orientation-migration models for the global plate tectonics of the last 200 Ma,the author proposed the following hypothesis:giant meteorites impact the lithosphere surface with different impact angles at different locations;such impacts could then sometimes induce mantle diapirs,causing plates to migrate radially or in one orientation depending on the impact angle.Thus,giant meteorite impacts in the periods of 200,170,100,65 and 0.78 Ma were all near vertical impacts to Earth's surface,as they induced mantle diapirs and led to radiating extension and migrations of the lithosphere plates.In contrast,the 138 Ma giant meteorite impact event could be an oblique impact to the Indian Plate;and in the period of 35 Ma,the microtektites event exhibited a very low impact angle to the Earth's surface.According to this new hypothesis,meteorite impact on Earth is a result of interplanetary gravity change within the solar system.