To reduce the error of a Hall current sensor caused by the variation of the conductor position, a new symmetrical dual-core four-air-gap magnetic circuit structure is designed. The proposed structure includes two symmetrically placed dual-air-gap magnetic cores and four Hall devices, where the two symmetrically placed dual-air-gap magnetic cores are used as the sensor magnetic circuit and the average voltage output from the four Hall devices is used as the output of the sensor. First, the output error of a traditional Hall current sensor caused by the variation of the conductor position is discussed, and the principle of reducing the error by using a symmetrical dual-core four-air-gap magnetic circuit structure is analyzed. Then, a finite element simulation was performed to mimic the magnetic induction intensity at the air gap of a single-core single-air-gap magnetic core and that of the proposed circuit structure. Then, the relative error of these two circuits was calculated. Finally, a prototype of the proposed circuit structure was manufactured. The simulation and experimental results show that the proposed circuit structure can significantly reduce the measurement error caused by the position deviation of the measured conductor, and the maximum measurement error is only 0.566% when the measured current ranges from 10 to 50 A.