The invention discloses a DNA fragment for peculiarly inhibiting Rab27B gene expression and the application thereof. A small interfering RNA provided by the invention is of a double-stranded RNA consisting of nucleotide sequences indicated by sequences 4 and 5 in a sequence table. The DNA fragment is shown in formula I, and SEQ forward nucleotide sequence is shown as sequence 2 in the sequence table; the SEQ reverse is complementary with the SEQ forward in opposite directions; and X is of an intron. The experiment approves that: when the DNA fragment is introduced to hepatic cell cancer cell, the Rab27B expressed protein is remarkably reduced, and the vitro proliferation capacity, vitro adhesion capacity, vitro migration capacity and vitro invasive capacity of HCC97H cell are remarkably reduced after the Rab27B is reduced. SEQ FORWARD - X - SEQ REVERSE (I).