Abstract: In order to investigate the failure laws of straight wall tunnel with a single radial crack under biaxial compression load, two cases are studied. One is the crack located in the arch shoulder to the vault with the vault semicircle center as the basis of radial crack. The other is the crack located in the tunnel bottom or arch wall, and the angle between the crack surface and the tunnel wall is fixed at 135 degrees. In the experiment, using model tests and numerical simulations, the test samples of cement mortar are investigated. The stress intensity factor and the stress chart of the crack tip are numerically calculated, and the simulated results are in good agreement with the experimental ones. The results show that: (1) The crack reduces the stability of the tunnel and the compressive strength. (2) When the radial crack is located on the arch shoulder or the vault with angle of 45°, the stability of the tunnel is the worst, and it is most easily damaged. (3) When the crack is located at the junction between the arch bottom and the arch wall, the tunnel is the most vulnerable, and the overall stability is the worst.