Optimization the performance of the Pebble Bed Reactor with OTTO fuel loading scheme has been carried out. Parameters and reactor desigen refer to the HTR-module 200 and PBMR. HTR-Modul 200 is model PBR that has thermal power output 200 MW and using UO2 as a fuel with HK loading 7 gr/pebble and uranium enrichment of 7.8%. The PBMR is a rptotype pebble bed modular reactor with an thermal output of 400 MW. The core has a annular shape with a fixed central graphite reflector.