A lamp structure for light steel frame comprises a lamp tube and two connectors respectively disposed at two ends of the lamp tube. The connectors have opening portions and snap-latch portions disposed to sides of the opening portions. The opening portions are fit to ends of the lamp tube. The snap-latch portions are used for clamping trusses of the light steel frame so that the lamp tube can be quickly and easily fastened to any position under the light steel frame without support of any tool. The structure adopts a single lamp tube to have light weight and modernity and improves the shortcoming of a light steel frame lamp in great volume.