  Precision measurements of leptonic mixing parameters and the determination of
the neutrino mass hierarchy are the primary goals of the forthcoming
medium-baseline reactor antineutrino experiments, such as JUNO and RENO-50. In
this work, we investigate the impact of nonstandard neutrino interactions
(NSIs) on the measurements of {sin^2 theta_{12}, Delta m^2_{21}} and {sin^2
theta_{13}, Delta m^2_{31}}, and on the sensitivity to the neutrino mass
hierarchy, at the medium-baseline reactor experiments by assuming a typical
experimental setup. It turns out that the true mixing parameter sin^2
theta_{12} can be excluded at a more than 3 sigma level if the NSI parameter
varepsilon_{e mu} or varepsilon_{e tau} is as large as 2% in the most
optimistic case. However, the discovery reach of NSI effects has been found to
be small, and depends crucially on the CP-violating phases. Finally, we show
that NSI effects could enhance or reduce the discrimination power of the JUNO
and RENO-50 experiments between the normal and inverted neutrino mass
hierarchies.
