Flow landslides are one of the deadliest disasters in the world. One of the landslide flow types that has received limited research is mudflow, particularly the effect of external parameters on the impact force. Most research on debris flow has employed numerical simulations to study debris flow, with a focus on material parameters. Today, numerous methods are available to simulate large-strain cases, such as the material point method. Therefore, this study aims to investigate the sensitivity analysis of the impact force on rigid barriers due to external mudflow parameters using the Material Point Method (MPM). The parameters simulated in this test were friction coefficients, initial flow depths, base inclination, and magnification scale. The most significant factor is the friction coefficient, with an approximately 167% increase in impact force resulting from a 30-fold decrease in the friction coefficient. The initial flow depth factor is the second most influential parameter, with base inclination at the last position. This study also simulated the effect when the model was magnified 256 times, showing that the impact force increased by approximately 167,000 times more than the initial impact force.