Abstract: Based on research of the stability of roadbeds in permafrost regions, an evaluation system for stability of roadbeds is constructed in this paper. Twelve factors influencing the stability of roadbeds are selected as the evaluation indices. Five aspects are considered in the evaluation system. They are permafrost type, temperature, thickness, geological conditions and project management. The safety reliability and relationships of each factor are considered. The fuzzy synthetic model is built by adopting AHP and fuzzy mathematics theory. And the fuzzy synthetic evaluation method is advanced based on the safety reliability. At last, the case of Qinghai-Tibet highway in Qingshuihe section is calculated and analyzed with the proposed method. The results are consistent with the field observations.