The best time to correct X-legs in children is between the ages of 3 and 5, and no later than 7 years old. Physiological knee valgus occurs during children’s growth and development, usually starting at age 3 and ending at age 7. During this period, if the ankle joint spacing is less than 5cm, usually do not need to be corrected, pay attention to observation, normal sitting posture can be, usually with the age of the growth of self-correction. During this period, if the ankle spacing is greater than 5cm, it is recommended to use corrective devices in time, such as braces, elastic bands, orthopedic shoes, etc., which are generally required to be worn for at least 8 hours a day, and to be reviewed in the hospital every six months to check the recovery of the X-shaped leg and to adjust corrective devices, and then end the treatment with the doctor’s permission when the knee valgus has recovered to less than 3~5cm. If the knee valgus is particularly severe, with ankle joint spacing greater than 10cm, or pathological knee valgus combined with other diseases, surgical treatment is recommended before the bones close.