CAS, Inst High Energy Phys, Beijing 100049, Peoples R China
; CCAST World Lab, Beijing 100080, Peoples R China
To experimentally study the charmonium. psi' cascade radiative decay, psi' -> gamma'chi(cJ) -> gamma'gamma J/psi, a generator which describes correctly all angular distributions is a necessity. We can determine the photon multipolarities (or equivalently the helicity couplings) by analyzing the angular correlations. In this work, a generator with fulls description of angular distributions for such process will be introduced, as well as the measurement method of multipolarities will be discussed, which can be implemented at BESIII/BEPCII or CLEOc.