This research uses basic principle of the rheological theory to realize the formation process of the accidents in the building construction process;analyzes the developing process of the single and multi rheological model of the building construction safety accidents;provides the variation of the these two models.This paper also presents the conception of safety accidents rheological strength;gives the calculation method of the rheological strength by using the theory of fault tree analysis;discusses the structure and probability sensitivity of the rheological strength under the model of multi rheological.