Flat feet often cause plantar fasciitis and changes in the appearance of the foot, as follows: 1, plantar fasciitis: because the arch of the flat foot will collapse, the normal plantar negative pressure will be changed, and the compound and stress on the plantar tendon membrane is significantly higher than the normal population, which is very easy to cause a long-term high tension state of the plantar tendon membrane. The plantar tendon membrane will undergo chronic strain, so pain will occur, especially in walking very little distance will appear on the bottom of the foot pain, which is the main symptom of flatfoot syndrome. 2, foot shape change: such as heel bone outward, inner ankle protruding, outer ankle becomes smaller, which are all due to the change of the flat-footed weight-bearing point of force.