Abstract：Refraction wave tomography is usually suitable for plane interface geological model. Here,refraction wave method is applied to tomography of velocity in two dimensional medium where there are curved interfaces. The assumption is made that an curved interface to he obtained consists of some plane interface segments. These plane interface segments are inversely derived one by one then combined into an approximate curved interface we want. We deduce time distance curve equation of plane interface refraction wave，by which inversion computation can be done segment by segment or interface by interface. Interval velocity as well as shape and depth of a curved interface in layered medium can be inversely derived by-using refraction waves to achieve tomography of two dimensional interval velocity.
