The invention discloses a structure of a two-sided and four-sided arc protective film and a preparing process of the arc protective film, and relates to the technical field of mobile phone protective films. The preparing process comprises the following steps: a. slitting a sheet into parts, slitting the sheet material into blank sheets with a working allowance size of a piece of protective film by using a cutting die; b. punching on the blank sheets, and punching positioning holes; c. placing the punched blank in a forming mold, performing hot-press forming with heating time about 5-10s, forming temperature about 60 DEG C and forming time about 5-10s, and carrying out hot-pressing on the sheet as the radian with the same size with a mobile phone screen surface; and d. cutting edge waste by using a side-cutting mold, tearing off two layers of PE protective films, cleaning and then packaging. The protective film is simple in structure, adopts a simple process, has a generous and fashion appearance, and can be well accepted by consumers.