  We derived the second post-Newtonian solution for the quasi-Keplerian motion
of a charged test particle in the Reissner-Nordstr\"om spacetime under the
harmonic coordinates. The solution is formulated in terms of the test
particle's orbital energy and angular momentum, both of which are constants at
the second post-Newtonian order. The charge effects on the test particle's
motion including the orbital period and perihelion precession are displayed
explicitly. Our results can be applied to the cases in which the test particle
has small charge-to-mass ratio, or the test particle has arbitrary
charge-to-mass ratio but the multiplication of the test particle and the
gravitational source's charge-to-mass-ratios is much smaller than 1.
