In view of some issues such as the lack of basic criteria and basis for 5000m geological core drilling, the great difference between oil and gas drilling and core drilling in drilling technology and equipment, this paper summarizes and systematically analyses the diameter size and tubing string specifications in deep geological core drilling at home and abroad. On this basis， basic external conditions and interrelated requirements are defined with calculation of annular hydraulics and design of the wire-line drill string strength for ultra-deep hole core drilling. The diameter size, drill string and casing string specification for 5000m ultra-deep hole drilling are preliminarily set up with the wire-line drilling process as the main part.