Abstract: In the absence of magnetic shielding room, the data measured with the low frequency magnetic measurement system using superconducting quantum interference device, could be easily interrupted by serious baseline wandering and harmonic power line interference, which are brought by the geomagnetic activity and the power line. In order to enhance the detection performance for weak magnetic signal, a new joint suppression method for baseline wandering and power line interference is proposed. In this proposed method, the signal is partially reconstructed with intrinsic mode functions decomposed by the noise assisted multivariate empirical mode decomposition. Consequently, the non-stationary effect brought by the baseline wandering could be eliminated. And then according to the short-time stationarity of the power line interference, the least square method is adopted for interference suppression. Numerical simulation and wild measured data processing results show that, compared with adaptive filter method, the proposed method achieves better performance for baseline wandering and power line interference, which indicates it is applicable to wild measurement without magnetic shielding room.