TMR current sensor has excellent characteristics such as high sensitivity, good temperature characteristics, and wide dynamic range, which can meet the new needs of smart grid development. However, the measured value of the output of the TMR current sensor changes with the change in the spatial magnetic field strength. External electromagnetic interference will bring large errors and DC bias to the measurement of the sensor, resulting in a narrowing of the measurement current range. Therefore, an electromagnetic interference compensation method for TMR current sensor is proposed. Two TMR chips are used to measure the synthetic magnetic field signal and the interference magnetic field signal, respectively. Then the output signals of the two TMR chips are compensated and reduced by the signal conditioning unit. The final output analog signal is the magnetic field intensity signal generated by the current of the line to be tested without interference. Finally, the effectiveness of the proposed method is verified by field tests.