A backlight and a liquid crystal module having the same are provided. The backlight comprises: a light guide plate, a light-guide-plate fixing element for fixing the light guide plate, and at least one light source disposed adjacent to the light guide plate, wherein the light-guide-plate fixing element is made of thermal-contractive material. As the light-guide-plate fixing element is made of thermal-contractive material, in a test environment of high temperature and high humidity, it is possible to ensure that the light guide plate can expand and contract freely without resistance; meanwhile; while at normal temperatures, as the tight-guide-plate fixing element is in contact with the light guide plate without gap therebetween.