Classical molecular dynamics simulation was used to investigate the structure, melting and mechanical properties of Au nanowires encapsulated in single-walled carbon nanotubes (SWCNT). A possibility of synthesizing controlled Au nanowires was firstly studied by encapsulating small clusters into CNTs with suitable diameters. The nanowires with multi-shell structure of cylindrical symmetry are predicted as a consequence of spontaneous and confined coalescence of gold clusters. The investigation of melting temperature and behavior of a gold nanowire with multi-shells in a carbon nanotube (CNT) showed that the melting temperature of the enclosed Au nanowire is lower than its bulk counterpart and higher than that observed for free-standing ones. Different from the melting behavior of freestanding Au nanowires, the melting of Au nanowires enclosed in CNTs with tube diameters (D) in the range of 1.08 nm < D < 2.09 nm investigated here was found to initiate from the center layers. Finally, the deformation behavior of the gold-filled single-walled carbon nanotube was simulated under axial compression. The results show that the buckling strength of the Au-filled carbon nanotube is increased compared with that of a hollow tube, and is similar to the case of filling with gases or fullerenes. The interactions between filling elements and the carbon wall help restrain the collapse of the tube. With Au-filling, the filled tube experiences an elastic-inelastic transition, somewhat like the behavior of metals, which is different from the cases when it is filled with gases or fullerenes, particularly for low filling density.