Abstract: By means of experiments and numerical simulations, diffraction and overpressure distribution of blast wave behind the explosion isolation wall were investigated. First of all, explosion experiments were conducted to study the explosion-isolation effect of the wall, based on which the time-histories of the shock wave at the same positions with and without explosion-isolation wall were obtained. Then, hydrodynamic code AUTODYN was used to simulate the diffraction process of the blast wave behind the wall, and the numerical model was verified by comparison with the experimental results. Parametric studies were carried out to investigate the influences of TNT equivalent, explosion distance, wall height and so on. Based on numerical results and dimensional analysis, the overpressure distribution behind the explosion-isolation wall was derived and empirical formula of the peak overpressure near the ground were also obtained, which can provide important reference for the design and safety assessment of explosion-isolation walls.