The invention relates to a method for reducing a hot rolling steel rail tread decarburization depth. According to the method, a stepping type heating furnace is adopted to heat, and air/fuel ratios of various segments are controlled; a depth of a decarburization layer of the heavy rail head portion is determined by the following formula shown in the description; and the heating process is performed according to the following manner: 1, heating is performed to achieve a temperature of 140-150 DEG C within the beginning heating time of 10-15 min, 2, heating is performed to achieve a temperature of 440-450 DEG C within the heating time of 18-23 min, 3, heating is performed to achieve a temperature 580-620 DEG C within the heating time of 3-7 min, 4, heating is performed to achieve a temperature of 950-1000 DEG C within the heating time of 6-10 min, and 5, heating is performed to achieve a temperature of not less than 1200 DEG C within the heating time of 20-25 min. According to the invention, the heavy rail tread decarburization layer depth can be less than 0.2 mm, the process is easy to control, and the qualification rate is increased and the train driving safety is enhanced.