In order to attenuate the blast shock wave in the tunnel efficiently， the design idea of setting up multiple continuous diffusion chambers in the tunnel was proposed. Based on the numerical simulation method， the influence of the structural parameters of the multi-stage diffusion chamber on the wave absorption efficiency was systematically discussed， and the propagation attenuation characteristics of the shock wave with a pressure of 2-11 MPa and a positive pressure duration of 18.25-1000 ms in the pit containing single， double/tertiary diffusion chamber were investigated. The results showed that the increase in the number of diffusion chambers can effectively improve the wave dissipation efficiency of the tunnel， and the peak pressure of the shock wave after passing through the three-stage diffusion chamber pit is 81.08% lower than the peak pressure of the straight pit without diffusion chamber with the same length， while the spacing between the diffusion chambers has a limited effect on the wave dissipation efficiency of the tunnel. Under the condition that the total length of the diffusion chamber is equal， the tertiary diffusion chamber has the best attenuation effect on the shock wave compared with a single long diffusion chamber and the secondary diffusion chamber. With the increase of shock wave pressure under the same positive pressure duration， the wave dissipation efficiency of the multi-stage diffusion chamber pit slowly increases. Under the same peak overpressure condition， the wave loss efficiency of the three-stage diffusion chamber pit decreases greatly with the increase of positive pressure time， but it can still maintain a wave loss efficiency of 43.38% when the positive pressure time is 1000 ms.