Aim To study the effect of 5F on tubulin polymerization.Methed 5F was added into the tubulin polymerization-depolymerization system and the changes of Absorption values at 350 nm, 37 ℃ were recorded. Results 5F decreased the Absorption values of the reaction system.and markedly inhibited not only tubulin polymerization but also tubulin depolymerization. Conclusion 5F inhibits tubulin polymerization and depolymerization, and leads to cell cycle arrested, and possibly induces apoptosis.