Abstract: The feasibility to evaluate wearing status of the bearing system by using the Superconducting Quantum Interference Device(SQUID) magnetometer was studied in this paper. To predict the status of the ferromagnetic particles in bearing oil from the magnetic field signals measured by SQUID, a scheme was also proposed and validated to reconstruct the distribution of magnetization in oil pipe from the measured signals. The experimental results verified that the SQUID was very efficient for the measurement of micro-magnetic field due to magnetic particles, and its signal amplitudes had clear correlation with the amount of the particles. In addition, the numerical results revealed that the proposed inverse analysis scheme and the developed code were applicable for the reconstruction of the distribution of magnetic particles. For magnetic signals even with 20% noise, the magnetization information inside a pipe could be properly reconstructed.