  JUNO is a multi-purpose neutrino observatory under construction in the south
of China. This publication presents new sensitivity estimates for the
measurement of the $\Delta m^2_{31}$, $\Delta m^2_{21}$, $\sin^2 \theta_{12}$,
and $\sin^2 \theta_{13}$ oscillation parameters using reactor antineutrinos,
which is one of the primary physics goals of the experiment. The sensitivities
are obtained using the best knowledge available to date on the location and
overburden of the experimental site, the nuclear reactors in the surrounding
area and beyond, the detector response uncertainties, and the reactor
antineutrino spectral shape constraints expected from the TAO satellite
detector. It is found that the $\Delta m^2_{31}$, $\Delta m^2_{21}$, and
$\sin^2 \theta_{12}$ oscillation parameters will be determined to better than
0.5% precision in six years of data collection, which represents approximately
an order of magnitude improvement over existing constraints.
