A fill light imaging apparatus (100, 400, 500), comprising an image sensor (130, 430, 530), an optical unit (120, 420, 520), a fill light unit (110, 410, 510), and a processor (150, 440, 550), wherein the image sensor (130, 430, 530) is configured to alternately generate a visible light frame and a fill light frame; the optical unit (120, 420, 520) is configured to form an image with light on the image sensor (130, 430, 530); the fill light unit (110, 410, 510) is configured to continuously fill light for a photographed object, wherein the fill light is non-visible light suitable for imaging; and the processor (150, 440, 550) is configured to combine a visible light frame and a fill light frame that are adjacent or consecutive, to obtain a composite frame; wherein the optical unit (120, 420, 520) is further configured to control a type of light that can shine on the image sensor (130, 430, 530); and when the image sensor (130, 430, 530) starts to generate the fill light frame, the processor (150, 440, 550) is configured to control the optical unit (120, 420, 520) to enable fill light to shine on the image sensor (130, 430, 530), and when the image sensor (130, 430, 530) starts to generate the visible light frame, the processor (150, 440, 550) is configured to control the optical unit (120, 420, 520) to enable the fill light not to shine on the image sensor (130, 430, 530); and wherein the optical unit (120, 420, 520) comprises a light filter switching apparatus and a single-pass light filter, wherein the single-pass light filter is configured to filter out a type of light other than visible light in an imaging light path of the optical unit (120, 420, 520), and the light filter switching apparatus is configured to place the single-pass light filter in or out of the imaging light path of the optical unit (120, 420, 520); and the processor (150, 440, 550) is further configured to: when the image sensor (130, 430, 530) starts to generate the fill light frame, control the light filter switching apparatus to place the single-pass light filter out of the imaging light path of the optical unit (120, 420, 520), and when the image sensor (130, 430, 530) starts to generate the visible light frame, control the light filter switching apparatus to place the single-pass light filter in the imaging light path of the optical unit (120, 420, 520). the image sensor (130, 430, 530) is configured to alternately generate a visible light frame and a fill light frame; the optical unit (120, 420, 520) is configured to form an image with light on the image sensor (130, 430, 530); the fill light unit (110, 410, 510) is configured to continuously fill light for a photographed object, wherein the fill light is non-visible light suitable for imaging; and the processor (150, 440, 550) is configured to combine a visible light frame and a fill light frame that are adjacent or consecutive, to obtain a composite frame; wherein the optical unit (120, 420, 520) is further configured to control a type of light that can shine on the image sensor (130, 430, 530); and when the image sensor (130, 430, 530) starts to generate the fill light frame, the processor (150, 440, 550) is configured to control the optical unit (120, 420, 520) to enable fill light to shine on the image sensor (130, 430, 530), and when the image sensor (130, 430, 530) starts to generate the visible light frame, the processor (150, 440, 550) is configured to control the optical unit (120, 420, 520) to enable the fill light not to shine on the image sensor (130, 430, 530); and wherein the optical unit (120, 420, 520) comprises a light filter switching apparatus and a single-pass light filter, wherein the single-pass light filter is configured to filter out a type of light other than visible light in an imaging light path of the optical unit (120, 420, 520), and the light filter switching apparatus is configured to place the single-pass light filter in or out of the imaging light path of the optical unit (120, 420, 520); and the processor (150, 440, 550) is further configured to: when the image sensor (130, 430, 530) starts to generate the fill light frame, control the light filter switching apparatus to place the single-pass light filter out of the imaging light path of the optical unit (120, 420, 520), and when the image sensor (130, 430, 530) starts to generate the visible light frame, control the light filter switching apparatus to place the single-pass light filter in the imaging light path of the optical unit (120, 420, 520).