The invention discloses a frame clamp for flexible line assembly of a motorcycle. The frame clamp comprises a lower bottom plate and an upper bottom plate hinged on the lower bottom plate, wherein the other end of the upper bottom plate is provided with a threaded through hole in which a first threaded rod is screwed; the end of the upper bottom plate, which is hinged with the lower bottom plate,is also hinged with a movable clamping plate; the upper surface of the upper bottom plate is also upwardly and fixedly provided with a front positioning plate; a first clamping plate is transversely arranged at the upper end of the front positioning plate; the end of the movable clamping plate, away from a hinge part, is provided with a second clamping plate corresponding to the first clamping plate; the middle part at the upper end of the first clamping plate is hinged with a second threaded rod; and a screw cap of which the diameter is greater than the width of a positioning groove is screwed on the second threaded rod. Through the frame clamp, different types of motorcycle frames are clamped and fixed on a flexible line traveling vehicle, so that stability and firmness of clamping and fixing are guaranteed. Meanwhile, the frame clamp has the advantages of convenience in operation, high safety, quickness for clamping, high machining efficiency and the like.