This paper contributes a novel proposal of a chemical sensor (CS) that is based on the elliptical rotated-hexacore photonic crystal fiber (ERH-PCF) for several chemical substances in the terahertz (THz) frequency regime. A full-vectorial finite element method (FEM) and perfectly matched layer (PML) frontier complaint are used to design this circular photonic crystal fiber (C-PCF) on software tools, and all numerical results in terahertz (THz) waveguide are achieved successfully. The proposed sensor shows maximum relative sensitivity (RS) that is 70.51%, 71.11% and 68.08% and less confinement loss that is 2.53 × 10^-03 dB/m, 2.77 × 10^-06 dB/m and 1.07 × 10^-02 dB/m with response to Ethanol (n = 1.354), Benzene (n = 1.366) and Water (n = 1.330) at 1 THz frequency respectively. Here, total power fraction (TPF), effective mode index (EMI), and effective area (EA) are also discussed details in consideration of the context of different industrial and medical applications.