Objective: To analyze characteristics and related factors of the plantar pressure during the level walking and single leg standing in the chronic ankle instability (CAI) individuals. Methods: From April 2019, 75 CAI individuals and 40 healthy individuals were enrolled in this study. Both of the static and dynamic plantar pressure were measured during six times level walking and three times single leg standing testing. The data including peak force, time to peak force in various foot contact areas and the time to boundary (TTB) and velocity of center of pressure (COP) were measured and compared between the affected side and the unaffected side and between the CAI cases and the healthy individuals. The correlations between the plantar pressure and the gender, Beighton score, affected side and body mass index (BMI) were analyzed. Results: The characteristics of plantar pressure distribution in the CAI individuals included: (1) During the level walking, the affected side showed the similar pressure contribution as the unaffected side (P>0.05). While compared with healthy individuals, there was a significantly higher peak force in the 5th metatarsal area (t=-3.86, P=0.03) of the affected side, lower peak force in the 1st (t=2.99, P=0.02), 2nd metatarsal head areas (t=2.09, P=0.01) of the affected side, medial hindfoot areas of both sides (affected, t=2.33, P=0.01; unaffected, t=3.74, P=0.02) and toes areass of both sides (affected, t=2.23, P=0.01; unaffected, t=3.28, P=0.02) and a delay to peak force in the 4th metatarsal head area (t=3.33, P=0.01) of the affected side. (2) During the single leg standing, the CAI individuals showed significantly worse balance control in the anterior/posterior direction (P<0.05) and lateral/medial direction (P<0.05) compared with the healthy controls, and the affected side had more severe balance control deficit in the lateral/medial direction (P<0.05). (3) The women (P<0.05) and the individuals with higher Beighton scores (P<0.05) showed worse balance control deficit in the lateral/medial direction. Conclusion: CAI individuals showed significantly a more lateral shifted plantar distribution during the level walking compared with the healthy individuals and the tendency was worse on the affected sides, and showed worse balance control in the anterior/posterior direction and lateral/medial direction during the single leg standing. The women and those with generalized ligament laxity showed significantly worse balance control.