A double closed loop cooperative control structure of a micro-plasma arc welding power source of the invention relates to the technical field of welding source and comprises an input rectifying filter circuit, a power switching element, an intermediate frequency transformer, an output rectifying circuit, and both ends of an output filter condenser (1) are respectively connected with the output rectifying circuit and one input end of a cooperative control closed loop circuit (3); the other input end of the cooperative control closed loop circuit (3) is connected with the detection end of a current control closed loop circuit (2), both output ends of the cooperative control closed loop circuit (3) are respectively connected with the input end of the current control closed loop circuit (2) and a tungsten bar (13), the feedback end of the cooperative control closed loop circuit (3) is connected with the power switching element, and the output end of the current control closed loop circuit(2) is connected with a workpiece (12). The double closed loop cooperative control structure reduces the volume and the weight of the micro-plasma arc welding power source and meets the demands of energy conservation and environmental protection, thereby realizing the technological parameter control of thin and precise structural member micro-plasma arc welding.