the regularization theory is a key tool for geophysical inversions. In this paper, two regularization parameters are introduced into the magnetotelluric (MT)-gravity joint inversion. The very fast simulated annealing (VFSA) method is adopted to optimize the objective functional of the joint inversion. In view of the randomness of VFSA method for model productions, a new adaptive method is proposed to determine values of the regularization parameters. The synthetic model test for different projects shows an effectiveness of the new approach for regularized joint inversions.