The invention discloses an excavation and supporting method for a tunnel crossing a high-angle thrust water-rich and sand-rich fault. A circuitous pilot tunnel and a drainage tunnel are arranged on asame side of a tunnel main hole. When excavation and supporting construction is carried out on a construction tunnel, the excavation and supporting method for the tunnel crossing the high-angle thrustwater-rich and sand-rich fault comprises the steps that 1, preliminary excavation and supporting construction is carried out on a rear side tunnel segment; 2, synchronous excavation and supporting construction is carried out on a rear side tunnel segment and a drainage tunnel body of the drainage tunnel; 3, the synchronous excavation and supporting construction is carried out on the rear side tunnel segment, the drainage hole body of the drainage tunnel and a rear side circuitous pilot tunnel segment; 4, the excavation and supporting construction is carried out on a front drainage tunnel body, a front pilot tunnel segment and a middle tunnel segment; and 5, the excavation and supporting construction is carried out on a front side tunnel segment. According to the excavation and supportingmethod for the tunnel crossing the high-angle thrust water-rich and sand-rich fault, the steps are simple, design is reasonable, construction is simple and convenient, the using effect is good, the tunnel hole is excavated by adopting a three-step method, full fracture surface supporting is carried out on the tunnel hole by adopting a double-layer preliminary supporting structure after excavation,and the safety of a later tunnel structure can be ensured.