Abstract: VSOP program package is widely used in the engineering design of the pebble bed high-temperature gas-cooled reactor with uranium fuel, but the applicability of VSOP code for pure plutonium fuel core is not completely proven. Uranium and plutonium were recycled from the 250 MW High-Temperature Gas-Cooled Reactor-Pebble-bed-Module (HTR-PM) spent fuel from the U-Pu fuelled core, and PuO₂ and MOX fuel elements were designed based on this recycled plutonium and uranium. These fuel elements were used to build up a new PuO₂ or MOX fuelled core with the same geometry of the original reactor. The random arrangement of coated fuel particles in the fuel pebbles and the random distribution of the fuel pebbles in the core were modeled as the repeated structure of regular shape in the Monte Carlo package MCNP. Based on the same reference of HTR reactor core, the core effective multiplication factors from VSOP model and Monte Carlo model were compared, and the causes of the differences were analyzed. Preliminary results show that the VSOP simulation result of the uranium fuel core accords well with the MCNP result, and the VSOP result of the pure plutonium fuel core is about 2% lower than that of MCNP code. Preliminary results demonstrate the applicability of VSOP code for pure plutonium fuel core, and the improve suggestions of the VSOP code were given.