Abstract：1-D layered medium model has been designed by analysing both the actual geoelectric structure of marine sediments in Jianghan basin and the statistical physical data taken from 5 boreholes there. The rnagnetotelluric data are simulated by using recursion formula for 1-D layered medium，and partial derivatives are computed by taking difference quotient method. The forward computation of seismic data is achieved by doing fast ray tracing on horizontal interface，and the partial derivatives are estimated by adopting analytic method. The theoretical data are derived from typical HAK curve and 5-layer geophysical model.Then，the joint inversion of magnetotelluric and seismic data is described in detalil. The inversion involves the following steps:Introducing the space vector of model，whose parameters consist of velocity，resistivity and thickness of each layer.Offering the response function of the model.Determining the mapping relation between the response function and data vector.Different data sets have different physical spaces and magnitudes，so that we must do normalization，for which we introduce relative prediction error vector that involves the use of the method for solving an ill-posed problem.Theoretical model and joint inversion of real data show that it is better than the inversion of any single kind of geophysical data.
