Abstract: By the reactions of three kinds of sodium poly vinyl alcohol of different average molecular weight with 1-(chloroacetyl)-5-fluorouracil(AF) or l-(2-chloro-propionyl)-5-fluorouracil (PF) in absolute DMSO, six kinds of new polymers were prepared. Meanwhile, the influence of reaction conditions and average molecular weight of polyvinyl alcohol on the new polymers was studied systematically. The structural characteristics of the new polymers were investigated by IR and UV; hydrolysis of the new polymers in various buffer solutions (pH1.5, 7.0 and 9.0) was measured by UV, and it was obvious that the new polymers could release out 5-FU.