A peridynamics method and system for tunnel rock mass failure water inrush catastrophe simulation. A calculation model is discretized into material points, and a virtual boundary layers is set on an outer side of a boundary of the calculation model as an object to which boundary conditions are applied; a size of a horizon of the material points is selected to form a neighborhood matrix; a crustal stress is made equivalent to a stress boundary condition of the calculation model, a karst cave water pressure is made equivalent to a normal pressure, and a displacement constraint and tunnel support are converted into a displacement boundary condition; a speed and a displacement of the material point are solved, and local damage situations are recorded; and a tunnel construction process is simulated by material point dormancy after initial balance calculation is stable.