Abstract: This article reports an accident about occupational skin harm caused by sulfurous iron ore slag in the course of dredging and draining it from the extretorY pool. There were 8 persons down into the pool, all suffered from skin lesions, The mild cases suffered mainiy from diffuse congestion and skin dryness,in between there were few shallow ulcers, Tn the serious cases ulcers coalesced into large patches accompanied with diffuse congestion, According to the investigation on the spot and patch tests, the author analysed and discussed the mechanism and etiology of the disease, suggested some relevant preventive and protective measures to be taken, and the result is quite satisfactory.