Abstract: OCCAM algorithm has been successfully used to invert transient Rayleigh wave dispersion curves for lower velocity layers.The new efficient algorithm can overcome such serious shortcoming as the strict dependence on initial model,improve shear wave accuracy and resolution using thinned layers and weighted matrix,and can enhance iterative effect and adjust the relationship between resolution and solution by self-adaptive iterative smooth factor.Inversion results of field data indicate that OCCAM algorithm is characterized by good stability,high accuracy and strong resolution,and can automatically invert shear wave velocity and thickness.