By using a numerical method developed in this paper,namely coupled Euler/Lagrange method,numerical simulations on seismic coupling effects induced by underground explosion with different explosion modes are carried out.Seismic coupling effects in tamped and cavity explosions in granite were studied.Dependence of decoupling factor on the initial cavity volume and the frequency were examined.It shows that the decoupling factor could reach 50 to 60 for completed cavity decoupling explosions in granite.