The embodiment of the present invention relates to the field of display technology, and provides a backlight source, a liquid crystal display panel and a liquid crystal display device. The backlight source comprises at least two light guide plates and a light source corresponding to the respective light guide plate. The light guide plates are joined to form a light guide plane, and the light source is arranged at the periphery of the corresponding light guide plate and does not transmit light to the other light guide plate. The light source corresponding to the respective light guide plate can be controlled by a control circuit. According to the present invention, it is able to reduce the power consumption of the screen and the backlight source and improve the endurance of the backlight source.