The invention discloses a three-phase program-controlled power source overheating protection method based on a multi-parameter physical model. The protection method comprises following steps: 1) detecting a current value and a voltage value which are output by a three-phase program-controlled power source, and monitoring the environment temperature during operation of the three-phase program-controlled power source by virtue of a temperature sensing unit; 2) establishing a heating model of a power amplifier for a current source, a heating mode of a power amplifier for a voltage source, a heat transmission model of the power amplifier for the current source and a heat transmission model of the power amplifier for the voltage source; 3) establishing an overheating protection strategy based on the four established models and performing independent overheating judgment, action and protection on each phase of the three-phase program-controlled power source. According to the method, the overheating protection control strategy is established, so that effective overheating protection for the power amplifiers is realized, real-time, effective, rapid and comprehensive protection for the power amplifiers in the three-phase program-controlled power source is realized, the service life of equipment is prolonged, the working performance of the equipment is improved, and the three-phase program-controlled power source overheating protection method has favorable application prospect.