As of the end of June 2022, there are 660 nuclear power units in operation worldwide, with a total installed capacity of about 394 million kilowatts. The main combustion feedstock of these nuclear power plants contains elements such as U-235, U-238, Pu-239, etc. These fuel nuclei undergo radiation capture, fission, transmutation, and other reactions with neutrons in the reaction vessel, which leave many nuclides with strong radioactivity and long decay cycles in the spent fuel after combustion and bring many problems to the disposal of spent fuel. Although the subcritical accelerated starter system (ADS) has a hard neutron energy spectrum and has certain advantages for transmutation of transuranic elements, its commercialization level is low, and transmutation of transuranic elements using pressurized water reactors (PWRs), which are more widely commercialized nowadays, can quickly and effectively alleviate the problem of spent fuel treatment in nuclear power plants. In this paper, the transmutation characteristics of transuranic elements in spent fuel in pressurized water reactors are investigated. In this study, transuranic elements in spent fuel are introduced into pressurized water reactor (PWR) fuel, and the changes in the effective multiplication factor and the neutron flux density distribution of PWR core assemblies are analyzed under different arrangement modes of transuranic elements. The results show that the introduction of transuranic elements into the pressurized water reactor core causes a decrease in the Keff value; moreover, the core neutron energy spectrum is hardened due to the capture and depletion of a portion of thermal neutrons after I-129 is added into the core.