Display device and vehicle-mounted display system

The invention discloses a display device and a vehicle-mounted display system. The display device comprises a backlight board, a display panel and side walls. The backlight board is arranged in a wayof being parallel to the first direction. The display panel is arranged in a way of being parallel to the second direction. The inclined angle between the backlight board and the display panel is an acute angle. The backlight board comprises a first end and a second end in turn in the first direction. The display panel comprises a third end and a fourth end in turn in the second direction. The inclined angle between the plane connecting the second end and the fourth end and the plane of the backlight board is an acute angle. The side walls comprise a first side wall and a second side wall. Thefirst side wall is connected with the first end and the third end. The second side wall is connected with the second end and the fourth end. The second side wall comprises a reflection structure. With application of the displ