A luminous system used for projecting a light beam to a plane, the luminous system comprising: a luminous component for generating a light ray; and an angle-adjustable device for adjusting a luminous angle of the light ray arranged between the plane and the luminous component and located on a route of the light ray, the angle-adjustable device comprising a first lens element, the first lens element comprising a light-emitting portion and a light-incident portion connected to the light-emitting portion, the light-incident portion comprising a recess opposite to the light-emitting portion and a plurality of light-guiding areas surrounding the recess; wherein an outer diameter of the light-emitting portion is larger than an outer diameter of the light-incident portion, and the outer diameter of the light-incident portion decreases along a direction away from the light-emitting portion, the light-emitting portion comprising a plurality of sub-lenses formed on a surface thereof and far away from the light-incident portion; wherein the angle-adjustable device further comprises a second lens element arranged between the first lens element and the plane, the second lens element comprising a light-incident surface close to the first lens element, a light-emitting surface opposite to the light-incident surface, and a plurality of micro-lenses formed on the light-incident surface and aligned with the sub-lenses, characterized in that the angle-adjustable device further comprises a carrier and a driving unit, the luminous component being disposed on the carrier and arranged beneath the recess, wherein the driving unit is connected to the carrier for adjusting the distance between the first lens element and the second lens element, and wherein the carrier includes a plurality of fixing arms, whereby a top end of each fixing arm has a supporting portion and an engaging component, which collectively fix the first lens element by nipping an outer edge of the light-emitting portion, such that when a motor of the driving unit is driven, the first lens element can slide upward and downwards from the second lens element; and in that the luminous system comprises a lens barrel, the lens barrel having an accommodating space, an upper opening, and a lower opening, wherein the upper opening and the lower opening communicate with the accommodating space, the upper opening is enclosed by the second lens, and the luminous component and the angle-adjustable device are arranged within the accommodating space, respectively; and in that when the distance between the first lens element and the second lens element is zero, the sub-lenses are in contact with the micro-lenses. a luminous component for generating a light ray; and an angle-adjustable device for adjusting a luminous angle of the light ray arranged between the plane and the luminous component and located on a route of the light ray, the angle-adjustable device comprising a first lens element, the first lens element comprising a light-emitting portion and a light-incident portion connected to the light-emitting portion, the light-incident portion comprising a recess opposite to the light-emitting portion and a plurality of light-guiding areas surrounding the recess; wherein an outer diameter of the light-emitting portion is larger than an outer diameter of the light-incident portion, and the outer diameter of the light-incident portion decreases along a direction away from the light-emitting portion, the light-emitting portion comprising a plurality of sub-lenses formed on a surface thereof and far away from the light-incident portion; wherein the angle-adjustable device further comprises a second lens element arranged between the first lens element and the plane, the second lens element comprising a light-incident surface close to the first lens element, a light-emitting surface opposite to the light-incident surface, and a plurality of micro-lenses formed on the light-incident surface and aligned with the sub-lenses, characterized in that the angle-adjustable device further comprises a carrier and a driving unit, the luminous component being disposed on the carrier and arranged beneath the recess, wherein the driving unit is connected to the carrier for adjusting the distance between the first lens element and the second lens element, and wherein the carrier includes a plurality of fixing arms, whereby a top end of each fixing arm has a supporting portion and an engaging component, which collectively fix the first lens element by nipping an outer edge of the light-emitting portion, such that when a motor of the driving unit is driven, the first lens element can slide upward and downwards from the second lens element; and in that the luminous system comprises a lens barrel, the lens barrel having an accommodating space, an upper opening, and a lower opening, wherein the upper opening and the lower opening communicate with the accommodating space, the upper opening is enclosed by the second lens, and the luminous component and the angle-adjustable device are arranged within the accommodating space, respectively; and in that when the distance between the first lens element and the second lens element is zero, the sub-lenses are in contact with the micro-lenses.