A system for monitoring a back light module is provided. The system includes an obtaining unit configured to obtain an intensity of output light from the back light module, a detection unit configured to detect whether the intensity of the output light from the back light module is greater than a preset value, and a control unit configured to control the back light module to reduce the intensity of the output light in response to detecting that the intensity of the output light is greater than the preset value, such that the reduced intensity of the output light is equal to or greater than the preset value.