Picosecond laser subtly crushes skin pigment through fast and powerful energy, then expel from lymph to thoroughly remove tattoo, colored patches. According to selectivity light thermolysis theory, the shorter of laser function time, the harder of the laser energy of target tissue absorbed and accumulated diffuse around tissue. The energy is limited to the needed repairing target to a certain extent, it protects the normal tissue around, then the repairing selectivity is stronger.