Based on nonFourier equations of heat conduction, using the complex function and conformal mapping technique, multiple scattering of thermal waves by subsurface defects of arbitrary shape in the semiinfinite slab was investigated. A general solution of thermal wave scattering was given. The thermal waves are excited at surfaces of solid materials by modulated ultrashort laser pulse with a adiabatic boundary condition for defects. The effects of geometrical and physical parameters on the temperature distribution are analyzed. Meanwhile, the numerical results of temperature variation were demonstrated. The analytic method and numerical results can be used for analysis of heat conduction, thermal wave imaging, physical inverse problem and evaluation of internal defects in materials.