Objective:To prepare a slow-releasing microsphere agent and assess its releasing effect.Methods:12rabbits were randomly divided into two groups:5-Fu group and5-Fu lipiodol microsphere group.During6hours after injection,at different time spots,HPLC was used to measure the concentration of 5-Fu in each of the two groups.Results:Density of 5-Fu lipiodol microsphere in hepatic tissue was obviously higher than that of 5-Fu during6hours after injection.Conclusion:The5-Fu lipiodol microsphere can elevate effective rate and have good slow-releasing effect.