Understanding the processes of morphological behavior in braided rivers and alluvial fan deltas is very important for river engineering purposes to manage hydraulic structures and prevent disasters from flood, and environmental purposes to maintain river ecosystem. A two-dimensional numerical model was developed to simulate braided rivers and alluvial fan deltas with erodible bed and banks. A moving boundary-fitted coordinate system was employed to calculate water flow, bed change, and bank erosion. CIP (Cubic Interpolated Pseudo-particle) method was used to calculate flow, which introduced little numerical diffusion. Sediment transport equation in the streamline and transverse wise, considering the secondary flow, was used to estimate bed and bank evolution in time. Bank erosion was simulated by following the procedure proposed by Shimizu (2002). Braided river in laboratory was reproduced for verifying the numerical model in the channel filled with nearly uniform sandy materials. Comparison of numerical results and experimental data has shown relatively good agreements. The evolution processes of the alluvial fan deltas were investigated numerically by controlling the sediment inflow, and the model reproduced the features of alluvial fan deltas, i.e., the successive aggradation, avulsion and then migration of a river.