The invention discloses a particle accelerator beam bending magnet, comprising main magnetic poles (1), main coils (2), guiding magnetic poles, guiding coils, upper, lower, left and right magnetic yokes, and multiple charged particle beams with properly different energy or particle types, which form a main magnetic field and a guiding magnetic field component; the multiple charged particle beams with properly different energy or particle types enter the bending magnet from different directions, and combined into a beam with the same track and direction after passing through the bending magnet;the main magnetic poles (1), main coils (2), guiding magnetic poles and guiding coils are used in an upper and lower paired manner, a certain gap is reserved between the upper and lower magnetic poles in each pair, a vacuum pipe is installed in the gap, and the beam can pass through the vacuum environment in the vacuum pipe. According to the particle accelerator beam bending magnet provided by the invention, the effect that the multiple beams are combined into one beam is achieved, the domestic blank is filled, and the long-term difficult problem that the particles with the same type and thesame energy cannot be combined into the same beam due to the same bending radius is solved.