In this paper, we present a new design of solid-core photonic crystal fiber (PCF), a Ge20Sb5Se75 substrate with a hexagonal lattice structure. The fiber characteristics are studied in the long-wavelength range (from 1.5 µm to 7.0 µm). A full modal analysis and optical properties of designed photonic crystal fibers with lattice constant Λ and filling factor d/Λ are presented in terms of chromatic dispersion, effective refractive index, nonlinear coefficients, and confinement loss. All-normal and anomalous flat dispersion with high nonlinearity and low confinement loss are the outstanding advantages of these photonic crystalline fibers. From there, three optimal structures with Ʌ = 2.0 µm, d/Ʌ = 0.35; Ʌ = 2.5 µm, d/Ʌ = 0.3 and Ʌ = 3.0 µm, d/Ʌ = 0.3 are selected and analyzed in detail for application in supercontinuum (SC) generation.