In order to find out how the branch structure affected the characteristic of shockwave propagation,LS-DYNA software was used to compute,and simulate certain shockwave propagating through the branch tunnels with different angle,and the overpressure/momentum(ratio)bench mark to measure "plane wave" was proposed.The results show that overpressure(ratio)bench mark is well suited for describing anomaly distribution,and momentum(ratio)bench mark can provide better measure for shockwave damage.Along with increasing of the branch deflexion angle,the primary tunnel momentum increases and the branch tunnel momentum decreases,and plane shockwave recover distance also increase but will not exceed six times equivalent diameter.