A liquid crystal display panel and a vehicle-mounted liquid crystal display device are provided. In the liquid crystal display panel, in an array substrate and/or a color filter substrate, a number of reflective interfaces in a functional area is greater than a number of reflective interfaces in a display area. Under the condition that an infrared optical transmittance is not affected, a reflectivity of light in the functional area is improved compared to the display area. This reduces or even eliminates a brightness difference between the functional area and the display area when a display is completely black.