The invention provides a heating tube laser welding clamp. The heating tube laser welding clamp comprises an operation table; the operation table is provided with a two-dimensional planar moving platform; the two-dimensional planar moving platform is provided with a clamping and compressing mechanism, a lifting mechanism is arranged beside the operation table; a temperature control tube fixing mechanism is arranged between the lifting mechanism and the clamping and compressing mechanism. The heating tube laser welding method comprises the following steps: fixing the tail of a long temperature control tube to be welded on the lifting mechanism through the temperature control tube fixing mechanism, and supporting the tail of a short temperature control tube to be welded on the clamping and compressing mechanism; sleeving the tops of the two temperature control tubes to be welded with ring flanges, and fixing the two temperature control tubes to be welded and the ring flange on the clamping and compressing mechanism respectively; putting the lifting mechanism down, aligning laser light with a welding position, and moving the two-dimensional planar moving platform on the operation table for welding. According to the device and method, a mature high-precision moving platform, a precise cylinder movement combination, a guide slide way slide block, the lifting mechanism and a fixing heating tube fixing mechanism are adopted, thereby realizing the advantages of small size and convenience and flexibility in operation.