We present an accurate theoretical technique to investigate electronic, electrical, mechanical and optical characteristic of metal@semiconductor ((4,0)@(8,0)) and metal@metal ((6,0)@(12,0)) double-walled carbon nanotubes. The simulation was conducted in the framework of a combination of DFT and Non-Equilibrium Green's Function (NEGF). The outputs reinforced that by decreasing interwall distance the p-conjugate delocalized electrons movement and the transmission characteristics of these sort of nanotubes are affected. Moreover, the obtained results showed the stability of double-walled CNTs with small interlayer distance due to the compatibility of the rotational symmetry of inner and outer tubes. Nevertheless, the electrical conductivity of (4,0)@(8,0) DWCNTs is extraordinary less than (6,0)@(12,0) DWCNTs and those of their internal and external SWCNTs separately. However, Young's modulus of DWCNTs (4,0)@(8,0) remained in Tetra Pascal range.