Divertor, one of the most challenging in-vessel components facing to plasma in a Tokamak device, is composed of tungsten or carbon fiber composites (CFC) mono-block of multilayer tube structure to withstand huge heat and particle flux. The multilayer tube bonded with hot isostatic pressing (HIP) welding technology is one of the key components for removing heat in divertor. The debonding defect in HIP welding surface may occurs due to fabrication and heat fatigue reason and may significantly reduce the heat transfer ability of the tubes. The debonding defect needs to be inspected in a nondestructive way to prevent local over heat and structural failure. In this paper, two kinds of EMAT probes are proposed to detect debonding defect in the multilayer tubes and their validity is valuated numerically by using a simulation code based on the formulation of reduce vector potential (Ar) method and the time domain difference scheme for wave propagation simulation.