The BESIII Experiment at the Beijing Electron Positron Collider (BEPCII) has accumulated
the largest $e^+e^-$ collisions data sets in the $\tau$-charm region in the world.
Using the data sets of $448.1$ million $\psi(3686)$ events and $1.3$ billion $J/\psi$ events, the branching
fractions and the angular distributions of $J/\psi$ and $\psi(3686)$ decay to $\Lambda\bar{\Lambda}$,
$\Sigma^0\bar{\Sigma}^0$, $\Sigma(1385)^0\bar{\Sigma}(1385)^0$ and $\Xi^0\bar{\Xi}^0$ are measured. The improved branching fractions
$\psi(3686) \to \gamma \pi^0, \gamma \eta, \gamma\eta'$ are reported.
The Dalitz decays of $\psi(3686) \to e^+e^- \chi_{cJ}$ and $\chi_{cJ} \to e^+e^- J/\psi$ are observed
and the branching fractions are measured. The Dalitz plot shows the point-like behavior of $\chi_{cJ}$.
The higher-order multipole amplitudes in $\psi(3686) \to \gamma \chi_{c1,2}$ with
$\chi_{c1,2} \to \gamma J/\psi$ are measured, as a byproduct the $\eta_c(2S) \to \gamma J/\psi$
transition is searched. The normalized magnetic-quadrupole (M2) amplitude for $\psi(3686) \to \gamma \chi_{c1,2}$
with $\chi_{c1,2} \to \gamma \gamma J/\psi$ and the normalized electricoctupole (E3) amplitudes for
$\psi(3686) \to \gamma \chi_{c2}$, $\chi_{c2} \to \gamma J/\psi$ are determined. With $\psi(3686)$
radiative decays, many new $\chi_{cJ}$ decays are observed for the first time, such as $\chi_{c0,2} \to \eta\eta'$,
$\chi_{c2} \to \eta'\eta', K(892)^*K$ and $\chi_{cJ} \to \Sigma^{+/0}\bar{\Sigma}^{-/0} $.
Improved measurements of $\eta_c \to \phi\phi$ and searches
for $\eta_c \to \omega\phi$ and $\eta_c/\eta(1405) \to \pi^+\pi^-\pi^0$ are reported.