The trapping characteristics of point defects in CdZnTe crystals grown by the vertical Bridgman method (VB) and the traveling heater method (THM) were analyzed. The photo-induced current transient spectroscopy (PICTS) was used to determine the traps' energy, their capture cross-section and concentration. Moreover, the trapping and de-trapping times of point defects were obtained. Furthermore, the photoconductive technology under sub-bandgap illumination were employed to study the influence of the trapping characteristics on mobility-lifetime (mu tau) product of CdZnTe crystal. The quantitative results indicated that sub-bandgap illumination can effectively improve carrier mobility-lifetime. The deep levels (Te-Cd), which occupy the position around the midgap, with high de-trapping time and low trapping time have greater effect on mu tau product for the crystals than Cd vacancies. The Te secondary-phase related defects, which can be observed in the VB method grown crystals, have less influence on it product than Te antisite.