About three fourth area of Taiwan is a hillside. In these areas, the steep topography and geological vulnerability make the landslides more likely to occur during torrential rainfall and typhoons. In recent years, because of the increasing torrential rainfall and typhoons, the rainfall-induced landslide has become more common in Taiwan. Therefore, risk assessment of rainfall-triggered shallow landslides has become important, and an empirical model for landslide risk assessment was proposed in this paper. The bi-factor model of using historical rainfall data (the hazard factor) and the landslide fragility curves (the vulnerability factor) was included in the proposed risk assessment method. The estimation of influence of rainfall and the fragility of shallow landslides were addressed in the paper. The use of the critical hazard potential (Hc) and critical fragility potential (Fc) were described by a case study of Shenmu Village in the Chen-Yu-Lan Watershed in Taiwan. The events of Typhoon Sinlaku (Sep. 2008) and Typhoon Morakot (Aug. 2009) were used in the case. This empirical model can express the probability of exceeding a damage state of landslides under certain conditions of rainfall intensity and accumulated rainfall. The results of this study indicated that the proposed method of risk assessment for landslide can be considered as a warning model in practice for disaster preparation and response.