The high frequency switch tube in the power electronic circuit will generate high di / dt current in the circuit loop, which will cause serious magnetic field interference to the adjacent loop and destroy the normal operation of the circuit, especially on the PCB with compact wiring. In order to reduce the magnetic field interference between the wires on the PCB, the article analyzes the coupling coefficient expression between the loops and extracts the characteristic quantities: the ratio of the distance d between the rectangular loops to the length a1 of the coil l 1—d / a1 , the ratio of the area of the two loops—A2 / A1 , and the center offset angle of the two loops α. And then the paper uses the finite element analysis method to analyze the relationship between the coupling coefficient kand each characteristic quantity. Morever, by analyzing the simulation data through MATLAB, the relationship curve between the coupling coefficient k and (d / a1 , A2 / A1 , α) is obtained, and the criterion to reduce the magnetic field interference between the PCB circuit loops is proposed basing on it. Finally, it is verified through experiments, which provides a basis for the parameter setting of the circuit loop on the PCB.