Abstract: Pebble-bed reactor analysis code COBBLE was developed by coupling deterministic neutronic calculation code CITATION and depletion code ORIGEN2 for the purpose of searching for equilibrium state of pebble-bed reactor with specified recirculation scheme. The spectra of all zones were calculated to modify the cross sections at different places of the reactor core. The equilibrium cycle was searched by an iteration procedure. A simplified version of pebble-bed modular reactor (PBMR) model with 6-pass random recirculation scheme was referred to as a benchmark test. Power and burnup distributions were calculated by COBBLE and compared with those obtained by PBRE code based on Monte Carlo neutronic transport program. Results show that COBBLE is suitable to analyze the equilibrium cycle of pebble-bed reactor.