Strength parameters are key factors that influence the sliding process of landslides and further affect the impact force on structures. Many scholars have previously studied the influence of strength parameters on slope stability; however, the influence of strength parameters on the impact force of flow-like landslides has not been analyzed till date. Therefore, in this study, the smoothed particle hydrodynamics (SPH) method was used to simulate the flow process of landslides and estimate the impact force on the rigid barrier by adjusting the strength parameters of landslides. The proposed SPH model was validated by a model test of dry sand impacting rigid barriers. The Gaoloucun landslide was selected as the study case and simulated to study the influence of parameters on the impact force. Finally, a multiple linear regression analysis was conducted to explore the sensitivity of impact force to input parameters and obtain the standardized regression coefficient, which was compared to find the dominant strength parameter. According to the results, among two strength parameters, the internal friction angle has more influence on the peak impact force than the cohesion.