Abstract: With the gradual extension of underground mineral resource exploitation to deep strata, the stress field of surrounding rock masses is rendered increasingly complex. Severe difficulties in rock fragmentation and unsatisfactory cut formation are frequently induced during the blasting and excavation of deep rock masses under high in-situ stress. To explore the damage evolution law of cut blasting under high in-situ stress and to optimize rock fragmentation and cavity formation effects, the rock breaking mechanism of second order segmentation wedge cutting is systematically elaborated. A three-dimensional dynamic damage constitutive model is constructed via the dynamic finite element method. Numerical simulations are implemented for multiple stress combinations in hydrostatic and non-hydrostatic in-situ stress fields, and the blasting performance is compared with that of traditional wedge cutting methods. Detailed analysis is conducted on the rock damage characteristics and cavity morphology formed by two-step wedge cutting blasting. The results show that, due to the differences in penetration depth and initiation time of secondary cut blastholes, new free faces are provided for secondary blastholes by primary blastholes, and the clamping effect at the rock bottom is mitigated. By two-stage timed initiation, rock masses are caused to undergo compression-induced failure followed by tension-induced fracture, by which the superposition of stress waves is realized and rock fragmentation quality is significantly improved. In hydrostatic in-situ stress fields, the radial cracking process is restrained with the increase of stress level. Cracks are developed in a uniform compression state, and the influence of in-situ stress on blast-induced cracking is transformed from promotion to restriction. The width of the blast fracture zone is continuously decreased, and rock damage is mainly concentrated in the vicinity of blastholes. Rock blasting damage characteristics are further complicated in non-hydrostatic in-situ stress fields. Due to the inhomogeneous stress field, directional differentiation and interweaving of cracks are induced, and the rock damage process is dominated by vertical stress. Under high in-situ stress conditions, cavities formed by primary cutting are presented in a conical shape, while cavities generated by secondary cutting are shown as a frustum shape. The cut cavity shape is constricted inward, and the damaged zone at the borehole bottom is reduced. To solve the above problems, six optimized cut blasting models applicable to high in-situ stress conditions are established. By adding empty holes and placing explosives at the bottom of the empty holes, rock fragmentation is improved to varying extents. The connectivity density of cracks between adjacent blastholes is increased, and the total cavity volume is raised by more than 10%. The proposed technology is proven to be suitable for the excavation of deep rock roadways under complex in-situ stress environments. The cut blasting effect is effectively optimized, and the utilization efficiency of blasting energy is improved.