A　model　has　been　developed　to　simulate　the　heat　transfer　behavior　during　spark　plasma　sintering　(SPS)　process　and　by　using　the　pure　spherical　copper　particles　as　an　example,　the　temperature　distribution　and　the　neck　size　evolution　of　the　powder　particles　have　been　studied.　There　is　a　greatly　inhomogeneous　distribution　of　the　temperature　in　the　particle,　and　the　growth　rates　of　the　necks　are　different.　The　obtained　simulation　results　show　a　good　agreement　with　the　experimental　measurements.　By　the　modeling　and　experimental　studies,　the　intrinsic　mechanisms　of　neck　formation　and　neck　growth　are　well　explained.