The　high　fusion　welding　hot　cracking　sensibility　of　the　next-generation　alloy　is　the　key　technological　difficulty　that　hinders　its　widely　application　in　the　aeronautic　and　astronautic　industry.　A　critical　review　of　the　fusion　welding　hot　cracking　from　the　perspective　of　basic　mechanism　and　the　experimental　research　of　typical　materials　was　presented　in　this　article.　The　fusion　welding　hot　cracking　phenomena　include　solidification　cracking　(occurs　within　the　fusion　zone)　and　liquidation　cracking　(occurs　at　the　interface　between　fusion　zone　and　partial　melting　zone).　The　formation　factors　of　the　fusion　welding　hot　cracking　include　alloying　composition,　welding　thermal　cycle　and　thermal　stress.　Based　on　the　comprehensive　understanding　of　the　formation　mechanism　of　the　fusion　welding　hot　cracking,　the　relative　research　progress　in　the　field　of　aluminum　alloys,　magnesium　alloys,　advanced　high　strength　steel　and　nickel　alloys　was　summarized.　The　establishment　of　the　quantitative　criterion　that　involves　the　effects　of　complicated　multi-component　and　the　morphology　of　the　dendrite　on　the　cracking　sensibility　is　the　key　development　direction.　Optimizing　the　alloying　composition　of　the　base　metal　or　filler　metal,　adding　nucleanting　agent　or　auxiliary　facilities　are　the　practical　method　for　restraining　the　fusion　welding　hot　cracking.　Conducting　the　research　on　the　mechanism　and　restraining　method　of　the　fusion　welding　hot　cracking　helps　to　solve　the　difficulty　of　the　next　generation　alloys　processing,　which　can　realize　their　application　in　the　field　of　aeronautic　and　astronautic　industry.　©　2022,　Journal　of　Materials　Engineering.　All　right　reserved.