Abstract Objective: To investigate the dynamic stability and stiffness characteristics of females with dynamic knee valgus during the landing phase of running, and to reveal the relationship between dynamic stability and joint stiffness, providing theoretical and practical references for injury prevention and rehabilitation in females with dynamic knee valgus. Methods: Participants were divided into two groups based on knee valgus angle: a dynamic knee valgus group (over 13°) and a normal group (0°~13°), each consisting of 16 individuals.The three-dimensional motion capture system, three-dimensional force platform, and wireless surface electromyography system were used to measure kinematic, kinetic, and electromyographic data during running. The margin of stability (MoS), joint stiffness, and electromyographic indicators were calculated, and difference tests and correlation analyses were conducted.Results: Compared to normal females, females with dynamic knee valgus exhibited greater peak knee joint moments in the sagittal plane (p=0.046) and greater changes in knee joint angles in the frontal plane (p<0.01). Females with dynamic knee valgus showed smaller MoSml (p=0.010), knee joint stiffnessml (p=0.042), and ankle joint stiffnessml (p=0.035). Prior to landing, the pre-activation levels of the gluteus medius (p=0.020) and vastus lateralis (p=0.021) were lower in females with dynamic knee valgus compared to normal females, while the pre-activation level of the lateral gastrocnemius (p<0.01) was higher. After landing, the co-activation ratio of the muscles around the hip joint (p=0.004) was higher in females with dynamic knee valgus compared to normal females. In normal females, there was a high negative correlation between MoSml and hip joint stiffnessml (r=-0.634, p=0.048). In females with dynamic knee valgus, there were high negative correlations between MoSml and hip joint stiffnessml (r=-0.600, p=0.042) and between MoSml and ankle joint stiffnessap (r=-0.673, p=0.024).Conclusion: During running, females with dynamic knee valgus exhibit characteristics of dynamic instability in the frontal plane and insufficient knee and ankle joint stiffness. The low pre-activation level of the gluteus medius and high activation level of the lateral gastrocnemius prior to landing reflect a distal compensation strategy due to insufficient proximal control. In females with dynamic knee valgus, there is a high negative correlation between dynamic stability and joint stiffness during running; the lower the dynamic stability in the frontal plane, the greater the ankle joint stiffness in the sagittal plane and the hip joint stiffness in the frontal plane.