To　study　the　material　deformation　behavior　of　titanium　retiary　sheet　in　numerical　control　incremental　sheet　forming　of　skull　defect　prosthesis　and　optimize　the　forming　process,　the　digital　model　of　the　defect　prosthesis　was　built　by　point　cloud　data　obtained　by　3D　scanner;　the　influences　of　mesh　size　on　forming　ability,　uniformity　and　stability　of　sheet　were　discussed　based　on　the　finite　element　numerical　simulation.　The　results　show　that　the　deformation　behavior　of　titanium　retiary　sheet　is　obviously　different　from　plain　titanium　sheet.　The　meshes　reduce　deformation　resistance　of　material　and　change　metal　flow　behavior,　which　leads　to　the　deformed　area　be　in　the　state　of　uniaxial　tensile　strain,　the　meshes　improve　the　deformation　ability　of　sheet,　but　the　uniformity　and　stability　of　the　formed　parts　get　worse　when　the　mesh　size　is　too　large.　When　titanium　retiary　sheet　is　used　to　the　incremental　forming　of　skull　defect　prosthesis,　the　mesh　diameter　should　be　Φ4　mm.　©　2020,　Editorial　Board　of　Journal　of　Plasticity　Engineering.　All　right　reserved.