The invention belongs to the power electronic technical field and provides a 12-pulse wave phase-controlled direct-current power source balanced charging-floating charging conversion control circuit.The circuit includes a power source, a balanced charging switch Ke, a floating charging switch Kf, a relay J, a time relay SJ, a first diode D1, a first electrolytic capacitor E1, and a balanced/floating charging signal generation circuit; the normally closed contact of the relay J is connected with a floating charge given branch circuit; and the normally open contact of the relay J is connected with a balanced charging given branch circuit. Conversion between balanced charging and floating charging is realized through action relationships among the balanced charging switch Ke, the floating charging switch Kf, the relay J and the time relay SJ. According to the 12-pulse wave phase-controlled direct-current power source balanced charging-floating charging conversion control circuit of the invention, the balanced charging/floating charging mode control of a phase-controlled direct-current power source is realized with a simple analog circuit structure and low cost.