The invention relates to a reflector for regulating light rays emitted by a light emitting diode light source to form an elongated light field. The length direction of the light field is an X-axis direction; the width direction is a Y-axis direction; and the direction perpendicular to the XY plane is a Z-axis direction. The reflector comprises a first reflection board, a second reflection board and a plurality of side boards, wherein the first reflection board is perpendicular to the XZ plane, the second reflection board is perpendicular to the XZ plane and is opposite to the first reflectionboard, and the side boards are arranged between the first and the second reflection boards and perpendicular to the XY plane; the first reflection board, the second reflection board and the pluralityof side boards are arranged into a circle to form a barrel-shaped structure; the barrel-shaped structure is provided with a first opening and a second opening opposite to each other; the light emitting diode light source is arranged at the first opening of the barrel-shaped structure; the first reflection board and the second reflection board are arranged inward along the Z-axle direction in an inclined way; and the projection of at least one of the first and the second reflection boards on the XY plane covers at least part of the light emitting diode light source.