This paper presents a new technique in strength reduction associated with finite element method for slope stability analysis. Cohesions and internal friction angles of soils are assigned as functions of temperature and used in strength reduction by changing nodal temperatures, so that the process of finding a factor of safety is transferred to the solution of a conventional thermal loading problem. The safety factor of a slope can be achieved in a single simulation process, without repeating the trial calculation. The increment of the thermal loading can also be automatically adjusted so as to accelerate the solving process.