Objective: To explore the transformation mechanism and change law of foot arch function during walking support through the analysis of walking gait parameters and foot arch mechanical structure. Methods: Eight subjects were recruited, and their gait parameters and transverse and longitudinal bow angles at different walking speeds were collected synchronously. Single factor repeated measurement analysis of variance (ANOVA) was used to test the difference of foot transverse and longitudinal arch angle and plantar force at different walking speeds. Results: During the period of walking support, there were two eigenvalues of longitudinal arch angle, transverse arch angle and plantar stress curve, and the eigenvalues of three curves were consistent under the changes of four kinds of walking speed. The results showed that when walking at 1.4 and 1.2 times the optimum speed, the time of forefoot push off phase was significantly higher than 0.8 times the optimal speed (P < 0.05), and the inflection point and the first peak value of the transverse arch were earlier than 0.8 times the optimal walking speed (P < 0.05). The minimum angle of the horizontal bow at 1.4 times optimal walking speed was significantly higher than that at 0.8 times optimal speed (P < 0.05), and the time at which the minimum angle appeared was significantly earlier (P < 0.05). The position of the second peak of the longitudinal arch was earlier than that of the optimal speed (P < 0.05). The position of the second peak of the longitudinal arch was earlier than that of the optimal speed (P < 0.05). Conclusion: (1) It is sufficient to realize the functional transformation of longitudinal arch and transverse bow when walking. In the walking support period, the longitudinal arch and the transverse arch of the foot together reduce the complete buffer, and the transverse arch and the longitudinal arch rise to lift the heel off the ground; in the off-ground stage, the longitudinal arch decreases again and the transverse arch of the foot rises, which increases the rigidity of the foot to complete the pedal and extension. (2) When carrying out the pedal extension propulsion function, the increase of step speed will increase the proportion of time in the gait support period, and the changes of foot transverse bow and longitudinal bow will advance with the pedal extension period. (3) The transverse arch of the foot rises before the heel leaves the ground and reaches the highest in the middle and later stage of pedaling off the ground. its arch structure contributes to the increase of the rigidity of the longitudinal arch and the transfer of the center of gravity on the coronal axis, so that the transverse arch of the foot rises and the longitudinal arch decreases to realize the transformation of the foot from elasticity to rigidity. The arch structure of the transverse arch plays an important role in the pedal and extension function of the foot.