Objective This study aims to elucidate the mechanisms of interface disruption between the actin filament and the membrane of cell pseudopodium that occurs during the breakage of the pseudopodium. Methods Time-lapse images of the behaviors of actin filament and membrane in the rupture process of cell pseudopodia were captured with confocal microscopy. A theoretical model of fracture of cylindrical interface was developed for analyzing the interface damage between actin filament and membrane in the breakage of cell pseudopodium. Molecular dynamics simulations were employed to simulate the breaking process of the cell pseudopodium, for comparison with the theoretical results. Finally, a finite element model considering the coupling of tensile-torsional deformation of actin filaments was developed to simulate torsional deformation of actin filaments under tension, both in the presence and absence of membrane. Results Our theoretical results indicated that there was an exponential relationship between the critical load for interface broken and the crack length. The critical load increases with the interfacial strength. The effect of the fiber diameter on the critical load depended upon the crack length, exhibiting different impacts for small and large crack lengths. Moreover, the finite element analysis suggested that the membrane substantially constrained the torsional movement when the actin filament was extended. Conclusions This study revealed the breaking process of cell pseudopodia and the mechanical mechanisms of the disruption of the interface between the actin filament and membrane. These results also shed useful light on the studies of cellular behaviors associated with pseudopodium breakage, such as the release of extracellular vesicles.