Seismic tomography allows geophysicists to discover the interior of the earth. First arrival travel time tomography can be used to image shallow subsurface models and to limit the location of anomalies in hydrocarbon exploration in layered sediment environments such as basalt and salt dome modeling. In this study, we use the eikonal equation, which is an approximation to the high-frequency wave equation, to model the first arrival time travel. There are different methods for solving this equation, the method used in this study is fast sweeping. The algorithm we use is based on rectangular grids. In the eikonal equation, we are faced with the travel times of the gradient, that to calculate this gradient, the adjoint-state method has been used.