Straightening comb is a comb-type high temperature electronic product used to straighten hair. Although it can straighten hair efficiently and quickly, it still causes a certain degree of damage to the hair. The principle of the hair straightening comb is to heat a high-efficiency hot plate through a hair dryer to release negative ions to make the hair smooth and straight. During the heating process, the hair scales will open due to static electricity. The concentration of negative ions in the straight hair comb is very high, which can eliminate static electricity and gather the hair scales, so as to achieve the purpose of smoothing hair.