Disclosed are a laser printer for pathological embedding cassettes and a printing method thereof. The laser printer includes an ink jet cartridge (3) filled with pigment ink, where a conveyor belt (6) is disposed below the ink jet cartridge (3), the semiconductor laser (4) is disposed on a side of the ink jet cartridge (3), and a photoelectric sensor (10) for detecting the position of an embedding cassette (1) is disposed on the conveyor belt (6). The beneficial effects brought by the printer and the printing method thereof are as follows: 1. By ejecting pigment ink droplets on an embedding cassette and irradiating the ink droplets with a laser beam from a semiconductor laser, the ink droplets have a rapid increase in temperature and are cured, so that colors are applied on a plastic surface and can be easily recognized. 2. With a combination of a guide groove and a semilunar pushing wheel, the conveyance of the embedding cassettes is implemented effectively to facilitate an operator in picking up and placing the embedding cassettes. 3. The position of an embedding cassette can be directly precisely detected using a photoelectric sensor, so as to ensure the precise irradiation of the ink droplets by the semiconductor laser, thereby improving the curing quality.