The　fast　development　of　the　emerging　research　topics　field　results　in　hundreds　of　theoretical　and　empirical　publications.　However,　to　our　knowledge,　there　is　no　comprehensive　and　objective　literature　review　on　this　field　until　now.　To　this　end,　a　citation　network　consisting　of　1607　papers　between　1965　and　early　2019　is　explored　to　discover　the　knowledge　diffusion　trajectory　of　the　emerging　research　topics　field　by　the　key-route　main　path　analysis　approach,　armed　with　the　traversal　weight　of　search　path　link　count.　From　the　convergence-divergence　patterns　in　the　local　and　global　main　paths,　the　development　of　emerging　research　topics　field　can　be　divided　into　three　different　stages:　the　emergence,　exploration　and　development　stages.　In　the　meanwhile,　several　research　drifts　can　also　be　observed:　(1)　from　citation-based　approaches　to　machine　learning　based　ones,　(2)　from　the　measurement　to　the　identification,　and　(3)　from　the　papers　to　the　patents.　Finally,　the　directions　of　future　research　are　suggested.