CAS, Inst High Energy Phys, Beijing 100049, Peoples R China
The construction of BESIII detector has been finished and the data taking is under plan. Some physics topics on charmonium decays at BESIII experiment are discussed in this paper. The measurement of properties of eta(c) and eta(c)' at BESIII is discussed and the expected precision of the measurement is estimated based on BOSS. Also the chi(cJ) decay and the measurement of hyperon decay parameters are mentioned.