Scientific ultra-deep well is the “telescope” for human observation on the deep earth. Obtaining undisturbed core in typical block to establish high resolution stratigraphic profile and physical & chemical profile is one of the most important purposes of the scientific drilling. In deep drilling, the drill bit driving mode and coring method are the key factors to affect energy consumption, construction period and project funds. The paper discusses some key technologies and difficulties in scientific ultra-deep core drilling and puts forward the specific solutions and research direction in several aspects.