In order to meet the needs for deep hole core drilling equipment in deep prospecting, scientific drilling and new energy exploration, research has been carried out to develop a complete set of 4000m geological core drilling technology and equipment. A top drive system is adopted in the rotary system of the 4000m geological core drilling rig to realize core drilling at high RPM, with the rotary table system placed at the bottom of the derrick to provide high torque and low RPM to meet different working conditions; the drilling tower and hoisting system allows tripping of long stands of drilling strings, cutting short the tripping time; and the rotary system can provides stepless variable speeds and the driller can operate the rig in a smart way through use of the international advanced all-digital AC frequency-conversion technology and automation, intelligent control technology, computer control technology, field bus communication and program control technology on the electric drive control system. The 4000m AC variable frequency drive core drilling rig has been used in Tianjin Dongli Lake Geothermal Survey Well (Well CGSD—01), and its technical performance has been preliminarily verified. It has the advantages of simple operation, high safety and reliability, low cost and so on. This paper introduces the background of the research program of 4000m AC Frequency-conversion Electric Drive Core Drill, as well as the current research situation at home and abroad, overall technical plan, main structure and characteristics, main technical parameters, field production trials.