Object It is very valuable to study the mechanical property of lumbar cancellous bone for the treatment of osteoporosis, bone remodeling, bone reconstruction, artificial joint replacement surgery and so on. This paper presents the impact tests of young and old lumbar cancellous bones, that definites whether the impact mechanical properties of old corpse spongiosa bone is different from younger’s. Methods In 1 hour of dying, forty specimens of lumbar vertebra L1-L5 were obtained from 4 corpses, aged 22,28，68,and 70 years old, and divided into young and old groups, twenty specimens in each group respectively. And every sample was slivered into 30mm long, 5mm extending and 5mm high along longitudinal direction.. Then each sample was carried on the impact experiment by the energy liberation method. The maximum impact energy of samples were demonstrated on the test machine and the impact toughness were calculated with a formula. Results The impact energy was （35.92±3.26）N·mm in youth group, and （28.2±2.94）N·mm in old group. The impact toughness in young group was （1.44±0.13）N·cm/mm2, （1.14±0.11）N·cm/mm2 in old group. It was indicated that the impact mechanical property of old person’s lumbar vertebra spongiosa reduced because the senile osteoporosis changed.