A special liquid crystal display backlight module based on U-shaped light guide plate was presented to reduce the thickness of side-in backlight module.Firstly, the curved side backlight module with 1 mm and 2 mm U-shaped light guide plate was designed and modeled by LightTools software. Then, two different thickness curved side backlight modules and a side-in backlight module with 4 mm conventional flat plate light guide plate were simulated and compared. Finally, the relative shifting simulation of the curved side backlight module with 2 mm U-shaped light guide plate was carried out and the results showed that the optical performance of the module had high stability in the strong vibration and wide temperature environment. Compared with the conventional side-in backlight module, the proposed curved side backlight module with 2 mm U-shaped light guide plate maintained the consistency of optical performance，which had certain reference significance for the thin design of special display.