Time information study of CsI(Tl) crystal calorimeter of BESIII

The read out system of BESIII-CsI(TI) calorimeter is based on FADC. The energy corresponds to the peak of signal waveform obtained by the scanning. In order to reduce the incoherent noise counts and improve the energy resolution a rough time information can also be fetched by counting the timing step number in FADC with a precision of 50ns besides the read out of energy information. The time information and the usage of this information in beam test axe presented and discussed.