In this study, micro structured core and cladding based O-PCF has been analyzed by its propagation characteristics. The effects of pitch variation, total power consumption and effective refractive index are investigated on O-PCF. The analyzing process takes place by the full vectorial finite element method (FEM). The analysis O-PCF contains five layers of the air holes in octagonal shape which increases relative sensitivity significantly and decreases confinement loss than the prior structures. Beyond that, the analysis O-PCF can sense the three chemicals water, Ethanol and Benzene at a wide range of wavelength.