In this article, here is developed a novel TOPASbased heptagonal photonic crystal fiber (H-PCF) for the identifi-cation of various chemical substances in the terahertz frequencyterritory. The full-vector finite element method (FV-FEM) is usedfor the numerical investigation about the competence of theproposed PCF. Simulation results show the maximum relativesensitivity as well as less connement loss for various chemicals.Numerically processed outcomes apparent that the proposedsensor shows 63.24 %, 61.05 % and 60.03 % detecting reactionsfor focused analytes benzene, ethanol and water individuallyat 1 THz frequency. Major purposes is to use H-PCF as theapplication of chemical sensor in commercial sector to detectharmful chemicals.