Existing numerical simulation methods cannot describe the weak-impact ignition behavior of reactive materials. Al/PTFE reactive material was selected as the research object. A model for the interface temperature rise between aluminum particles and polytetrafluoroethylene under impact loading was obtained by combining theoretical analysis and numerical simulation. This interface temperature rise model was embedded into the material point method （MPM） program framework. A numerical simulation method for the weak impact ignition characteristics of reactive materials was thus established， which is dominated by interface temperature rise. To validate the effectiveness of this method， impact ignition experiments on the reactive material were conducted using a split Hopkinson pressure bar （SHPB） apparatus. Compared with the MPM-SICR numerical simulation method that assumes a uniform temperature of the matrix and metal particles as the dominant factor for the reaction， the interface temperature rise of the reactive material under a shock wave pressure of 4 GPa is 750 ℃， which is significantly higher than the uniform temperature rise of 432 ℃. Under weak-impact conditions， the uniform temperature rise is insufficient to reach the ignition condition of the reactive material. In contrast， the interface-temperature-rise-based method can effectively simulate the deformation， fragmentation， and ignition phenomena of the reactive material. The relative error of the ignition delay time between the simulation and the experiment is 9.09%. This result demonstrates that the proposed method has high simulation accuracy for weak-impact ignition of reactive materials.