In this paper, we propose a D-shaped plasmonic optical biosensor based on photonic crystal fiber (PCF) to detecting of the different materials such as water, blood plasma, Yd-10B and hemoglobin by using of the refractive index. The gold layer is coated on the polished surface of D-shaped fiber. To achieve the highest sensitivity of the proposed biosensor, we investigated the effects of variation of the gold layer thickness and the other structure parameters such as hole diameter (d) and the distance between two holes or Pitch (L). The results show that the most sensitivity of the proposed biosensor is 2506 nm per refractive index unit (nm/RIU) with the resolution of 1.25×10^-5 RIU, when d=1.4 µm and Λ=1.9 µm with the gold layer thickness of 45nm.