The invention relates to a backlight module with wide amplitude and even light, which can be used as light source by installing in lamp house by assembling one or a plurality of modules. The invention comprises a straight tube type light source, an even light reflection board with multi turning surfaces and an even light bowl. The reflection board with multi turning surfaces and even light respectively comprises a reflection area, a lens diffuse mixing reflection area and a diffuse reflection area from central line to two sides, and each reflection area is formed by one or more than one reflection surfaces, and positioned under the straight tube type light source. The even light bowl is positioned above the straight tube type light source, and provided with a rhomboidal beam orifice, and the edge is in randomly scattered tooth shape, and the face facing the light source is the lens reflecting surface, and the face facing the display surface is the diffuse reflection surface. The design of three areas solves the difficulty of reflected light distribution and control. Reflection ray can be reflected in a cross way in the distance by the even light bowl, and the light ray can be gentler. The effective use rate of the module reaches about 90 percent, wide amplitude reaches 500 to 600 mm, and lighting evenness reaches more than 90 percent. Moreover, the advertising light box thickness is controlled between 70 mm to 50 mm.