Abstract: Use of MOX fuel in nuclear reactors is an effective way to dispose of plutonium. A large PWR reactor core with full core loading UO₂ fuel was referenced, the reactor core physics parameters of PWR with whole and part core loading MOX fuel were calculated by using DRAGON and DONJON codes, and the reactivity worth of control rods and boron acid solution were researched under loading MOX fuel. The results show that PWR core with MOX fuel can achieve the desired cycle length and power distribution, but loading MOX fuel will significantly decrease the reactivity worth of control rod and boron acid solution, moreover, the proportion of loading MOX fuel is positive to the decrease degree of reactivity worth.