Abstract：The paper briefly analyzed several objective functions of models in current geophysical inversion, and on the basis of the basic theory of imaging approach by focus inversion introduced a new stable function in objective function of MT inversion to replace the objective function of model under the traditional minimum structure or maximum smoothing criterion. Through study on the process of solving the optimum problem by adaptive normalized conjugate gradient approach, making the tests of several typical models and correlating the results with that by traditional inversion algorithms, it can show the correctness of the method in the paper and higher computational precision. Finally, the imaging processing of focus inversion was carried out on the real MT line data in Lei-Qiong depression, which showed higher correctness of the result in comparison with the same lin-e's seismic data.
