The error of reduction to pole in the low magnetic latitude area was revealed,and a study was made of study simulated annealing inversion of magnetic data.By subdividing the grid into cube elements and filling them with magnetic field parameters,magnetic interface can be simulated and inversed.In combination with the nonlinear characteristics of simulated annealing algorithm,a study was made of the modeling method with easy and flexible way of adding constraints,and magnetic anomaly model was established with complex structure.Feasibility is proved through model test and field data processing