The utility model discloses a mobile crane detection device, comprising a liftable triangular bracket, a laser level meter and a red filter lens, wherein the liftable triangular bracket comprises a support rod; a thread is arranged at the top end of the support rod; the top end of the liftable triangular bracket is connected with a supporting plate; a rail which is arranged all around a long nut supporting plate matched with a thread is arranged at the center of the lower side of the supporting plate; vertically and horizontally interlaced reinforcing ribs are arranged on the lower side of the supporting plate, and are connected with long nuts; a circle of refining rib is arranged on the periphery of the lower side of the supporting plate; the laser level meter is arranged in the supporting plate, and comprises a laser head with the power being 200MW for emitting a red laser; and the red filter lens is worn by a worker. The mobile crane detection device has the beneficial effects of simple structure, reasonability in design, accuracy in reading, time saving, manpower saving, convenience and fastness according to the narration of the scheme.