INTRODUCTIONrn4,4′-Diaminostilbene-2,2′-disulfonic acid(DAS) is an important intermediate which is widely used in synthesis of fluorescent whitening agents, direct dyes and reactive dyes[1,2].So far, the conventional procedure using Fe as catalyst for the production of DAS in China is greatly limited, due to industrial waste water, high labor intensity and low production capability. The electrochemical reduction method has been reported[3] overseas, but it is not suitable for China considering its large equipment investment, lower yield and great power consumption. Compared with the methods mentioned above, the catalytic hydrogenation method has attracted a great deal of attention in view of its simple and easy operation, high production capacity and high production efficiency[4-6].The relatively cheap Raney nickel is not used here since it shows a low safety performance in preparing DAS at a high reaction temperature and high pressure. In this paper, highly reactive and recyclable palladium-carbon is chosen as the catalyst. DAS of high purity and high yield is prepared under mild conditions. The catalytic hydrogenation method is a prospective method in producing DAS.