A manufacturing process of air cushion sock includes mixing materials into elastic threads and cotton threads as sock material; knitting the sock material to form a sock body having a length about twice that of the air cushion sock; placing a shaped air cushion bag on one half portion of the sock body; folding the other half portion of the sock body onto one half portion of the sock body to cover the air cushion bag; turning over an opening of the sock body a predetermined length to position the air cushion bag; filling air into the air cushion bag; sealing the opening of the sock body by sewing to form the air cushion sock; and turning over the air cushion sock.