A modified (HC-800) Photonic Crystal Fiber (PCF) using Gold nanoparticle as an active plasmonic material was used as bio a sensor. The Finite Element Method is used to compute numerical interpretations of sensing performance employing various liquids such as (Liver Blood, Colon Blood, Human Blood Plasma, Water, and Pentanol). In the proposed biosensor the sample (analyte material) is placed into a core, cladding air holes, and outside of the HC fiber structure. The sensitivity was calculated before and after adding the gold layer. The maximum amplitude sensitivity was found to be 769.5749 RIU-1 for Human blood Plasma and the best electric field was found to be 400V/m. In the same liquid when used the deposited PCF with a gold layer the maximum amplitude sensitivity was found to be 975.5352 RIU-1 at a best electric field of 477 V/m. And when the proposed sensor is considered as a refractive index sensor, where is it used the analyte samples only (inside the core and air holes) of PCF. The maximum amplitude sensitivity was found to be 869.8453 RIU-1 at a best electric field of 434 V/m.