Twenty-one novel fluorine-containing 2, 5-diketopiperazine derivatives(2a-2u)were synthesized by using N, N-diacetyl-2, 5-diketopiperazine, allylbromide, 2-fluorobenzaldehyde and other aromatic aldehydes. The structures were characterized by 1H NMR, 13C NMR, and HRMS. The cytotoxicities were evaluated against ten human tumour cell lines(K562, U937, MOLT-4, HL60, HeLa, DU145, MCF-7, A549, SGC-7901, H1975)by using CCK8 assay. Results showed that compounds 2a, 2d, 2e, 2f, 2g, 2h, 2k, and 2t showed significant cytotoxicity against U937(IC50=0. 2 μmol/L), HeLa(IC50=0. 5 μmol/L), and DU145(IC50=0. 7 μmol/L), respectively. Compound 2t could become a lead compound for further development for anticancer agents.