The invention discloses a power source device for a dental machine grid-control cold cathode X-ray tube, and belongs to the technical field of medical apparatuses and instruments. The power source device for the dental machine grid-control cold cathode X-ray tube is structurally composed of a high-voltage power source (1), a grid electrode power source (2), a single-chip microcomputer board (3), a grid-control bulb tube (4), current detection (5) and a closed-loop control panel (6). The power source device for the dental machine grid-control cold cathode X-ray tube is technically characterized in that the power source device does not need to be heated through filaments, the grid electrode power source is used for controlling the dental machine grid-control cold cathode X-ray tube to be opened and be closed, and the grid electrode power source controls tube current and forms closed-hoop control with the tube current. The power source device for the dental machine grid-control cold cathode X-ray tube has the advantages that a grid electrode switch ensures steepness of a leading edge and a lagging edge of a high-voltage wave form, the grid electrode power source and the tube current from closed-loop control to carry out dynamic adjustment on grid electrode voltage and the tube current, and current stability of the dental machine grid-control cold cathode X-ray tube is improved.