The algorithm and program of forwarding and inversion of magnetotelluric(MT) is proposed and verified. And provide the geophysics interpretation for borehole-to-Surface MT and controlled source audio MT(CSAMT) and make it more complete and effective. Deduce the nonlinear conjugate gradients(NLCG) algorithm on the basic of Rodi(2001), and improve the program to achieve seafloor condition. And verify the validity of the program. Finally, compare the forwarding and inversion on land with it in tunnel, and find that the noise is suppressed and the resolution is enhanced with setting the survey station underground.