Medical cosmetic lasers are a revolutionary contribution to the treatment of birthmarks. In the past, like coffee spots, nevus of Ota and some superficial large-sized hemangiomas often did not have good treatment means, and even if the disease was cured, it would often leave scar, which would affect the appearance and limb function, or leave a lifelong disability. However, for nevus, naevus and giant nevus, the only way is still surgery. The color of the nevus may become slightly lighter after several laser treatments, but it will not get rid of the root of the disease, and the possibility of cancerous changes increases after several stimulations.