To investigate the influence of initiation methods on the blasting effect of double wedge ultra-deep hole cut blasting, a three-dimensional numerical model was established using LS-DYNA software, and the rock-breaking effects under four different initiation methods are studied. The blasting effects were evaluated from three aspects: effective stress, rock mass dynamic damage, and blasting cavity formation, and the optimal initiation method for double wedge ultra-deep hole cut blasting was determined. The results show that forward initiation and central initiation result in low fragmentation degree at the tunnel face, easily causing problems of large blasting blocks and toe rock residues; the energy generated by reverse initiation and mixed initiation mainly acts on the hole bottom and tunnel face, which is conducive to rock fragmentation and throwing; under the same conditions, the mixed initiation method effectively solves the problems of rock block rate and toe rock residues, achieving the best cut effect. Reference can be provided by the research conclusions for similar projects such as tunnel excavation and rock roadway driving.