A lighting fixture, comprising: a lamp body, a light source component and an optical element; the lamp body and the optical element forming a closed cavity, the light source component being accommodated in the closed cavity; the light source component including a light source substrate and a plurality of light emitting units located on a front surface of the light source substrate, and the optical element being located in a light emission direction of the light emitting unit; wherein the light source substrate includes a back surface facing away from the front surface, the lamp body is formed with a heat dissipation structure, and the heat dissipation structure is in contact with the back surface of the light source substrate, wherein the lamp body includes a lamp cover portion and a mounting portion, the lamp cover portion including a front cover portion and a rear cover portion, an inner surface of the front cover portion extending to form the heat dissipation structure; wherein the heat dissipation structure includes at least one first fin portion; the first fin portion includes a plurality of fin posts spaced apart from each other; and each fin post is in contact with the back surface of the light source substrate and is aligned with one light emitting unit and wherein the heat dissipation structure further includes at least one second fin portion; and the second fin portion is in contact with the back surface of the light source substrate and is staggered from the light emitting unit, and wherein the second fin portion and the first fin portion are arranged at an interval; and wherein the lighting fixture further comprises a seal ring; and the seal ring is provided at a connection between the lamp body and the optical element and wherein one of the second fin portions includes a plurality of first positioning posts spaced apart from each other and wherein a first positioning hole is formed on the light source substrate with respect to one of the first positioning posts and a connecting member is inserted through the first positioning hole to connect the light source component with the second fin portion. the light source component including a light source substrate and a plurality of light emitting units located on a front surface of the light source substrate, and the optical element being located in a light emission direction of the light emitting unit; wherein the light source substrate includes a back surface facing away from the front surface, the lamp body is formed with a heat dissipation structure, and the heat dissipation structure is in contact with the back surface of the light source substrate, wherein the lamp body includes a lamp cover portion and a mounting portion, the lamp cover portion including a front cover portion and a rear cover portion, an inner surface of the front cover portion extending to form the heat dissipation structure; wherein the heat dissipation structure includes at least one first fin portion; the first fin portion includes a plurality of fin posts spaced apart from each other; and each fin post is in contact with the back surface of the light source substrate and is aligned with one light emitting unit and wherein the heat dissipation structure further includes at least one second fin portion; and the second fin portion is in contact with the back surface of the light source substrate and is staggered from the light emitting unit, and wherein the second fin portion and the first fin portion are arranged at an interval; and wherein the lighting fixture further comprises a seal ring; and the seal ring is provided at a connection between the lamp body and the optical element and wherein one of the second fin portions includes a plurality of first positioning posts spaced apart from each other and wherein a first positioning hole is formed on the light source substrate with respect to one of the first positioning posts and a connecting member is inserted through the first positioning hole to connect the light source component with the second fin portion.