Objective To investigate the gait characteristics of school-age children with generalised joint hypermobility (GJH). Methods The kinematic and kinetic data of lower extremity joints in 56 children with GJH and 56 healthy children were collected by 3D motion capture system and 3D force plates, and the differences between the two groups were compared and analyzed. Results Kinematics parameters: the mean ankle inversion angle(P=0.000),maximum hip adduction angle (P=0.002) and maximum foot clearance angle (P=0.004) in stance phase decreased in the GJH children group, while the mean foot progression angle (P=0.000), the maximum foot internal rotation angle(P=0.000) in stance phase, and the knee flexion angle (P=0.032) in the middle stance phase increased. Kinetics parameters: the maximum power of knee (P=0.005), and hip(P=0.000), joints and the maximum inversion moment of ankle joints (P=0.009)in stance phase decreased in GJH children group. Temporal and spatial parameters: the step length (P=0.001), walking velocity (P=0.000), and cadence (P=0.000) decreased in GJH children group, while the stance phase percentage(P=0.000), and step width(P=0.000) increased. Conclusions There is a decrease in walking efficiency and balance stability of children with GJH. The line alignment is abnormal in ankle joint. The knee joint function needs long-term attention.