The melting point of a free metal cluster is well known to increase with its size, and to usually be much lower than the melting point of the corresponding bulk material. The melting of free metal nanoparticles starts from their surfaces. However, in the current work, a different pattern of melting points of gold nanoparticles confined between two-layer graphene nanosheets (two-layer GNSs) was observed based on molecular dynamics simulations. The simulations indicated a decrease in the melting temperature with an increasing length of the confined gold nanoparticle. This relationship can be explained by the melting mechanism revealed from results of a Lindemann index analysis and the confining effect of the two-layer GNS.