Abstract: The time-average and instantaneous calculations of CANFLEX bundle with MOX fuel in a CANDU reactor are performed, and computational results demonstrate that the maximum bundle power and channel power are under the permissible limits. The transition from natural uranium core to MOX loading core is feasible without major modification of core structure and operation mode. An advanced PWR/CANDU synergism fuel cycle using MOX fuel are proposed and studied. It is estimated that the implementation of advanced PWR/CANDU synergism fuel cycle for Qinshan Phase Ⅲ NPP will increase the burnup to 13900MW·d/t（U）, save Natural Uranium resource 181t/a, and decrease the spent fuel to be disposed～128t/a in comparison with separate PWR and CANDU fuel cycle.