Abstract: Leak before break (LBB) analysis is very important to guarantee the safety of the pressurized equipments in a nuclear reactor. Although it has many advantages, it is not mature to apply in the gas cooled reactors (GCRs). To develop more accurate leak rate models are the key point for the applications of LBB analysis in the GCRs. Literature study was carried out concentrating on leak rate models proposed or used in LBB analysis. In each model, basic assumptions, equations for model development, experiments validation, numerical calculation and application examples were presented. From this literature study, key factors of leak rate models and their effects were analyzed and summarized, which give suggestions and instructions to new leak rate model development in the near future for the GCRs.