Abstract: The pebble-bed high-temperature gas-cooled reactor employs dispersed fuel elements and a unique fuel management strategy, which poses significant challenges for calculating fission product release from the reactor core. Traditional full-core release calculations use a lumped-parameter method with the FRESCO-II code, which cannot account for the inhomogeneous temperature distributions within fuel spheres, the variations in nuclide production rates, or the stochastic nature of pebble flow—leading to less accurate results. This work investigates a refined diffusion calculation method based on inventory calculations and the steady-state heat conduction equation, and develops a pebble-wised full-core release calculation approach using the Monte Carlo method. Under equilibrium core conditions, comparisons of in-sphere concentration distributions and release rate variations are made between the refined model and the conventional model, and the total release rates as well as release distributions for representative nuclides are determined. The results indicate that, compared to the model assuming a uniform temperature field and constant production rates, the inhomogeneous temperature field with variable production rates leads to lower release rates for individual pebbles. Furthermore, the distribution of release rates for short-lived nuclides in the core is strongly influenced by both the core temperature and neutron flux distributions, whereas long-lived nuclides are primarily affected by the temperature distribution.