Abstract: By placing the windings in the outer leg of EE cores, the magnetizing inductor and leakage inductance of highfrequency transformer designed with suitable windings and air gap can meet the requirement of parameters for LLC converter. And the two inductors of LLC converter and the high-frequency transformer can be integrated in one EE core, so the number of magnetic components can be decreased, and the power conversion efficiency and power conversion density can be increased. Meanwhile, because of the integrated magnetic LLC resonant technique, the ZVS turn-on can be achieved for the primary side power switch, and the ZCS turn-off can be achieved for the secondary side rectifier diodes under the whole load ranges. The converter losses can be decreased dramatically. Finally, a welding power supply prototype with 2.5 kW constant voltage output was developed. The experimental results show the performance of integrated magnetic LLC converter was improved.