Among all of primary school students activities, landing movement is commonly seen during daily playing or sports classes. Improper landing will lead to lower body injury easily. The present domestic and foreign related researches focus on analysis adult athletes. This research thus focuses on primary school students of Hsin-Shih Primary school, Taoyuan county and compares the kinematics and dynamics characteristic differences of third, fourth, fifth, and sixth-graded students' jumping to the same height (40cra) by bare-foot The information reference of biomechanics are analyzed by one-way ANOVA method (α=.05). When the differences reach a certain level, the differences will be compared by Scheffe methodology. The analysis indicates that: (1) During an instant vertical landing with falling speed of zero, among the angels of lower body's joints, only the knee joints pose an obvious difference but there is no difference among the elapse times. (2) The angular displacement, time to the first peak force (PK1) and second peak force (PK2) of ground reaction force of vertical landing will increase in proportion to the increase of age. (3) Except the hip joint, during the elapse of landing, the biggest angel velocity and exact timing are nearly the same. The PK1, PK2 and the passive impulse in less than 50 mini-seconds will tend to decline in proportion to the increase of age. Finally, the difference of reaching the first peak force pulse among students of all grades doesn't exist. For the measurement of the second peak force of impulse, the higher-graded students pose some difference. Thus, it is advised that primary school students be taught to exploit the bending of hip joints so as to reduce the huge impact of landing repercussion and also to avoid possible relating injuries.