Abstract: Nuclear clocks, the high-precision optical clocks based on nuclear energy level transitions, are deemed to have better timing accuracy than atomic clocks, the current gold timekeeping standard. Related research has great scientific and strategic significance for the development of our society. The development of ultra-precision thorium nuclear clocks since 2003 is investigated using the bibliometric method. Scientific knowledge maps are used to show the current macro (national-level), meso (institutional-level), and micro (personnel-level) distributions of research forces, main research topics, and main funding agencies in the field of nuclear clocks.