At present, one difficulty encountered in the decommissioning of pressurized water reactors (PWRs) is the disposal of spent nuclear fuels. To start with satisfying the power grid demand, from the perspective of fuel management, reducing the amount of assemblies in the reactor can reduce the amount of spent nuclear fuels and improve fuel economy performance. Taking CPR1000 with 18-month reloading strategy as example, the study of the two cycles before decommissioning and multi-units fuel management are carried out, and the operation mode of the long and short units is designed considering the transportation demand of one-time reloaded assemblies. The results show that two cycles use separately 72 and 48 fresh assemblies with 4.95% U-235 enrichment before the decommissioning, to achieve a similar length to the original fuel management equilibrium cycle with 72 fresh assemblies with 4.45% U-235 enrichment, and the design results meet the safety criteria. Compared with the 4.45% enrichment fuel management, 20 fresh assemblies are reduced. By using 4.95% U-235 enrichment assemblies, two cycles with 52 fresh assemblies loading patterns are designed to quickly use the one-time loaded from the decommissioning units. The results show that the cycle length meets the requirements and brings a total economic benefit of 264 million yuan to the nuclear power plant.