There is a probability of recurrence after picosecond laser spot removal, picosecond laser is mainly through the wavelength of the subcutaneous accumulation of pigment cells broken, so as to achieve the purpose of removing spots, spot removal of picosecond laser is only able to treat the skin that has already appeared pigmentation, and can not prevent the reappearance of pigmented spots. It is suggested that after using picosecond laser treatment, hydroquinone cream can be applied on the surface of residual pigmentation, together with oral glutathione and vitamin C, to achieve the reduction of the probability of recurrence. Avoid direct sunlight in daily life, otherwise ultraviolet rays will stimulate pigment cells, make pigment cells proliferate and trigger skin pigmentation. After picosecond laser treatment of pigmented nevus, local skin will appear flushing, burning, even itching, breaking and other symptoms, can be used with the use of humanoid collagen milk for coating, can reduce the laser for skin irritation changes.