Abstract: In-depth science teaching in primary and secondary schools is an important lever to serve the strategy of revitalizing the country through science and education. In response to the pain points of “knowledge indoctrination， process formalization， and surface level ability” in current science teaching in primary and secondary schools， the goal is to promote science teaching from “shallow coverage” to “deep understanding”. Through literature review， case analysis， and other methods， this study systematically explores the occurrence mechanism， performance patterns， and improvement strategies of deep science teaching in primary and secondary schools. From the perspective of the mechanism of scientific deep teaching， deep teaching is an educational extension of deep learning， which requires a support system based on the five dimensions of “goals content methods evaluation atmosphere resources”， and is directly influenced by teachers’ knowledge， teaching， and student perspectives； The process of its occurrence is a dynamic process of two-way interaction between teachers and students based on teaching resources and content. At the level of manifestation， deep science teaching has six core characteristics： deep integration of subject knowledge， rich and effective teaching frameworks， diverse and flexible learning methods， profound and comprehensive teaching evaluation， extensive and thorough student cognition， and meticulous student critical thinking. At the strategic level， it is necessary to strengthen teacher training and optimize curriculum design， implement innovative teaching methods， and improve teaching evaluation mechanisms. This study reveals the mechanism and manifestation of in-depth teaching in scientific disciplines， which can provide practical reference for the implementation of core literacy goals under the new curriculum standard.