The personnel evacuation mode of Mawan Undersea Shield Tunnel is studied by software pathfinder. Firstly, the theoretical model of personnel evacuation route is established. And then, the influence of spacing of stairs, slides and "cross passages+stairs" on personnel evacuation is studied and the safe evacuation range is analyzed. The study results show that: (1) The optimum spacing of stair evacuation mode of Mawan Undersea Tunnel is 80 m, and the optimum spacing of slide evacuation mode is 60 m. (2) The evacuation effect of slide is better than that of stair under the same conditions. The slide evacuation mode is recommended when the spacing is 60-70 m. (3) When the spacing of stairs is 60-80 m, the spacing of cross passages can be appropriately increased. While the spacing of stairs is 80-90 m, the spacing of cross passages should not be too large. (4) When fire occurs in the tunnel, the optimum way to evacuate is opening the exhaust ports of upstream and downstream, and only opening the exhaust port of downstream is the secondary choice.