We studied n-type conduction characteristics using p-type BiOCl by oxygen vacancy formation at the exposed (001) surface. This formation of oxygen vacancy at the surface of BiOCl nanosheets, confirmed by ACTEM, XPS and Raman spectra that oxygen vacancy gradually increasing as a function of UV illumination time. The low temperature PL result shows decreasing band edge emission of BiOCl due to high density oxygen vacancies were placed under conduction band edge of BiOCl. The conductivity dependence on oxygen partial pressure reveals n-type characteristic behavior as oxygen vacancies were present.