A downlight, comprising: a light source apparatus, comprising a light source panel and a lighting bead, wherein the light source panel has a light exit face arranged for the lighting bead and a heat conduction face disposed opposite to the light exit face; a heat dissipation set, comprising a heat dissipation annulus and a heat radiation plate, wherein the heat dissipation annulus includes a heat dissipation cylinder provided with an accommodation cavity and a annular heat dissipation flange located at an opening of the accommodation cavity and in connection with the heat dissipation cylinder, and wherein the accommodation cavity is configured for accommodating the heat radiation plate and defining an opening, and a surface of the heat radiation plate connected to the heat conduction face completely covers the heat conduction face, the light source panel being connected to the heat radiation plate through the heat conduction face, and being configured to guide light outward through the opening of the accommodation cavity, wherein a bottom of the accommodation cavity, the heat radiation plate, and the light source panel are sequentially arranged along an exit direction of the light, and wherein the light source panel and the heat radiation plate respectively define a gap relative to an inner wall of the accommodation cavity; and wherein the heat radiation plate is spaced apart from the bottom of the accommodation cavity, wherein the downlight further comprises a driving structure connected to the heat radiation plate and configured to drive the light source apparatus, wherein a bottom of the accommodation cavity defines a connecting hole, and the connecting hole penetrates to an external space of the accommodation cavity, and wherein the heat dissipation set further comprises a connecting post passing through the connecting hole, with one end of the connecting post connected to the heat radiation plate and the other end of the connecting post connected to the driving structure. a light source apparatus, comprising a light source panel and a lighting bead, wherein the light source panel has a light exit face arranged for the lighting bead and a heat conduction face disposed opposite to the light exit face; a heat dissipation set, comprising a heat dissipation annulus and a heat radiation plate, wherein the heat dissipation annulus includes a heat dissipation cylinder provided with an accommodation cavity and a annular heat dissipation flange located at an opening of the accommodation cavity and in connection with the heat dissipation cylinder, and wherein the accommodation cavity is configured for accommodating the heat radiation plate and defining an opening, and a surface of the heat radiation plate connected to the heat conduction face completely covers the heat conduction face, the light source panel being connected to the heat radiation plate through the heat conduction face, and being configured to guide light outward through the opening of the accommodation cavity, wherein a bottom of the accommodation cavity, the heat radiation plate, and the light source panel are sequentially arranged along an exit direction of the light, and wherein the light source panel and the heat radiation plate respectively define a gap relative to an inner wall of the accommodation cavity; and wherein the heat radiation plate is spaced apart from the bottom of the accommodation cavity, wherein the downlight further comprises a driving structure connected to the heat radiation plate and configured to drive the light source apparatus, wherein a bottom of the accommodation cavity defines a connecting hole, and the connecting hole penetrates to an external space of the accommodation cavity, and wherein the heat dissipation set further comprises a connecting post passing through the connecting hole, with one end of the connecting post connected to the heat radiation plate and the other end of the connecting post connected to the driving structure.