  Dark matter and dark energy dominate the behavior of our universe. The dark
matter usually forms halo structures in large number of galaxies. Properties of
dark matter halo can be revealed and understood from the gravitational lensing
observations. In this work, a comprehensive study on the gravitational lensing
of black holes immersed in dark matter halos is presented. To effectively model
the supermassive black hole in a galaxy center (which is surrounded by dark
matter halo) in a simple way, we investigate the Schwarzschild black hole and
charged Reissner-Nordstr\"om black hole immersed in a perfect fluid dark matter
halo. In the present work, several basic quantities in gravitational lensing
(the gravitational deflection angle of light, photon sphere, black hole shadow
radius, gravitational lens equation and Einstein ring) are calculated and
analyzed analytically and numerically. A second order analytical expansion of
gravitational deflection angle is obtained in the weak deflection limit, and
the full gravitational deflection angle (including all order perturbation
contributions applicable to both weak and strong deflection limits) is also
calculated numerically as comparisons. It enables us to analyze the perfect
fluid dark matter influences on gravitational deflection angle and
gravitational lensing beyond the leading order, which were not sufficiently
studied in previous works. Assuming $M \sim \lambda_{\text{DM}} \sim Q$, our
results show that dark matter can greatly influence the gravitational lensing
of central black holes.
