Study of charmonium spectroscopy at BESIII

In this talk, we will present the results on the charmonium spin singlet states below the open charm threshold, including h_c, \eta_c, and \eta_c(2S). The masses, widthes, and production rates of these states will be reported. The results are based on a data sample of 106 million \psi' events collected with the BESIII experiments at the BEPCII collider.