A real-time magnetic localization method based on unscented particle filter (UPF) is proposed to solve the problem for real-time localization of underwater non-cooperative magnetic targets. The state space model of non-cooperative magnetic targets is set up according to its motion characteristic, and the state is estimated in real time by UPF. In order to improve the observability of the system, the particle state is constrained and magnetic moment is inverted by the least square method. The simulation results and ferromagnetic object localization experimental results show that the method is good in localization precision and real-time performance, which can be applied to the real-time magnetic localization in near field.