The expression and significance of blood-testis-barriar tight junction protein as well as Occludin in the testis of mice was investigated after whole-body exposure to electromagnetic pulse (EMP). Thirty adult Balb/c mice were irradiated to the whole body with 400kV/m EMP and 200 repeat while other thirty adult Balb/c mice were sham irradiated in the same condition. Specimens were harvested to prepare paraffin-embedded slice or to extract tissue protein and mRNA on 1, 7, 14, 21 and 28 days after irradiation. Changes in cellular localization and expression of Occludin were examined by Real-time PCR, Western-blotting and immuno-fluorescence method, respectively. The results showed that the mRNA and protein levels of Ocludin expression were significantly decreased on 1, 7 and 14 days after irradiation compared with control groups. These results indicate that EMP can reduce the expression of blood-testis-barrier tight junction protein Occludin and induce the damage of blood-testis-barrier.