  X-ray flux from the inner hot region around central compact object in a
binary system illuminates the upper surface of an accretion disc and it behaves
like a corona. This region can be photoionised by the illuminating radiation,
thus can emit different emission lines. We study those line spectra in black
hole X-ray binaries for different accretion flow parameters including its
geometry. The varying range of model parameters captures maximum possible
observational features. We also put light on the routinely observed Fe line
emission properties based on different model parameters, ionization rate, and
Fe abundances. We find that the Fe line equivalent width $W_{\rm E}$ decreases
with increasing disc accretion rate and increases with the column density of
the illuminated gas. Our estimated line properties are in agreement with
observational signatures.
