The invention discloses a light source for photodynamic therapy, comprising a main light source, a plurality of auxiliary light source, a laser device, an optical fiber splitter and a controller. Themain light source is vertically disposed right above the work face, and the auxiliary light sources are disposed at the periphery of the main light source in a symmetrical and circling manner, havingan included angle with the main light source. The spot diameter of the main light source and the auxiliary light sources is larger than the maximum diameter of an irradiating area. The irradiating area includes a photosensitizer. After a laser machine outputs laser to the main light source and the auxiliary light sourced, a fiber splitter distributes and outputs light energy in proportion to the main light source and the auxiliary light sources. The controller is respectively connected to the laser machine, the main light source and the auxiliary light sources, and is used for controlling theturning on and turning off of the laser machine and the lightening sequence and lightening time length of the main light source and the auxiliary light sources. The invention is advantageous in that the light irradiation strength of the irradiating area can be flexibly regulated in the photodynamic therapy; with the composite nano photosensitizer materials, the treating effect of the specific position can be improved, and the damage of the peripheral areas can be reduced.