Charged Lepton Flavor Violation (CLFV) is highly suppressed in the Standard Model (SM) by the finite, but tiny neutrino masses. Its branching fraction is calculated to be extremely small in the SM and so far no CLFV process has been found in experiments, including searches performed in lepton ($\mu, \tau$) decays, pseudo-scalar meson ($K, \pi$) decays, vector meson ($\phi, J/\psi, \Upsilon$) decays, Higgs decays, etc. This talk presents the CLFV searches at the BESIII experiment. The process $J/\psi\to e\tau / e\mu$ is searched for using about 10 billion events collected by BESIII and the results improve the previously published limits by about two orders of magnitude.