We propose a star-shaped photonic crystal fiber (PCF) structure with a carbon disulfide (CS2) core, characterized by flat dispersion and elevated nonlinearity, aimed at facilitating high-coherence octave-spanning supercontinuum generation (SCG). The optical properties of the CS2-core PCF were investigated through numerical simulations by varying structural parameters. Two optimized CS2-core PCF structures were identified for achieving optimal bandwidth and high-coherence SCG. The first fiber, designated as #F1, has a lattice spacing of Λ = 1.8 μm. By pumping with a 100 fs input pulse at 1554 nm and a power of 1000 W, a flat octave-spanning SC extending from 1113 to 2357 nm can be generated. The second fiber, referred to as #F2, has a lattice spacing of Λ = 1.3 μm. By pumping with a 50 fs input pulse at 1750 nm and 1500 W, a highly coherent SC ranging from 1225 to 2350 nm can be generated. This research presents a new PCF design for generating high-coherence octave-spanning SC that can be applied in biosensing, spectroscopy, and other fields.