The invention discloses a laser annealing device and a laser annealing method for compensating a wafer heat map. The laser annealing device comprises a pumping laser source array consisting of a plurality of pumping laser sources, wherein each pumping laser source emits pumping laser; an annealing source for emitting annealing laser; and an adjustable mask piece. The adjustable mask piece is excited after being radiated by the pumping laser, and then becomes to enable at least one part of the annealing laser to be transmitted. Thereby, the laser annealing for compensating the heat map is achieved by converting the heat map into the transmittivity of the adjustable mask piece for laser annealing and then converting into the power of each pumping laser source. In one preferred embodiment, the pumping laser source array, the annealing laser source and the adjustable mask piece are arranged coaxially, and the adjustable mask piece rotates to be radiated by the pumping laser source array and the annealing laser source which are fixedly arranged at intervals with certain angles, and then the laser annealing for continuously compensating the whole heat map even the whole wafer is achieved.