The invention relates to a hot bending method for a U-shaped hanger rod for a boiler. The method comprises the following steps: step I, packaging a to-be-heated part of straight round steel with a heating plate, and heating the to-be-heated part for austenitizing the to-be-heated part, wherein heating length is obtained by adding 100 mm to length of a bent section of the U-shaped hanger rod left and right; step II, moving the heated straight round steel to a hot bending tool to be subjected to bending, ensuring the temperature of the straight round steel subjected to hot bending to be greater than the temperature of a metal phase line Ar3, and keeping the temperature for 1-2 minutes; and step III, putting the U-shaped hanger rod subjected to hot bending into a heating furnace to be subjected to destressing annealing treatment, wherein a charging temperature is lower than or equal to 400 DEG C, a heating range is an area obtained by adding 100mm to a circular-arc section of the U-shaped hanger rod left and right, diameter of a heated straight section is not smaller than that of straight round steel, the temperature in the heating furnace is increased to 720+/-20 DEG C at a speed smaller than or equal to 220 DEG C per hour and carrying out heat preservation for 240 minutes; and then, taking out the U-shaped hanger rod, wherein a discharging temperature is lower than or equal to 400 DEG C. According to the hot bending method, work output of manual bending can be reduced, and bending efficiency and quality can be improved.