The double laserpulses was used to therapy the skin pigmented disease.The thermal model of skin was built.And the thermal and acoustic injurys to the tissue in the double laser pulses therapy were analysed on the basis of the skin thermal model.The results shown that the acoustic injury of skin was decrease in the double laser pulses therapy,and the therapeutic effectiveness was improved.In order to reduce the tissue thermal injury the time space between the double laser pulses must be four times of the tissue thermal relaxation time at least.This theoretical analyses were verified by the pathological test.