As the major energy absorption of helicopter in crash， the buffer plays an important role in the safety flight of helicopter. A combined oleo-pneumatic and foam-aluminum helicopter buffer is proposed in this paper. Based on the theoretical calculation model of plastic collapse stress and finite element model， the impact crushing stress-strain of single aluminum foam is calculated and simulated. Then the calculation and simulation results are verified. Furthermore， the theory and simulation model are verified by impact crushing test of single aluminum foam. The dynamic characteristics curve of aluminum foam collapse is integrated into the dynamic model of combined oleo-pneumatic and foam-aluminum landing gear， and the crashworthiness performance simulation analysis is carried out. The results show that the peak load of the combined oleo-pneumatic and foam-aluminum buffer is reduced by 38%， and the buffer efficiency is increased by 12.7%. The crashworthiness performance of helicopter landing gear buffer is improved effectively.