Sodium　lignosulfonate　amine　(SLA)　was　synthesized　by　Mannich　reaction.　The　lignin-modified　waterborne　polyurethane　(WPU)　with　different　branched　structures　was　designed　and　prepared　by　introducing　SLA　as　a　hydrophilic　chain　extender.　The　effect　of　the　introduction　manner　of　SLA　on　the　performance　of　WPU　was　systematically　investigated.　The　results　showed　that　the　addition　of　0.75　wt%　SLA　in　an　appropriate　introduction　manner　can　prepare　a　polyurethane　dispersion　with　good　stability　and　high　solid　content.　The　tensile　strength　of　the　SLA-modified　WPU　film　was　significantly　improved　to　37.3　MPa.　The　SLA-modified　WPU　film　also　exhibited　high　water　resistance　and　thermal　stability.　Moreover,　in　the　introduction　manner　of　WPU-C,　the　adhesive　properties　of　SLA-modified　WPU　adhesives　were　also　improved,　which　was　mainly　attributed　to　the　entanglement　of　long　branched　chains　generated　by　SLA　chain　extension　with　other　polyurethane　chains　and　the　formation　of　physically　cross-linked　networks　through　the　interaction　between　functional　groups.　Therefore,　the　introduction　of　a　small　amount　of　sodium　lignosulfonate　amine　in　an　appropriate　manner　can　significantly　improve　the　performance　of　WPU　with　high　solid　content,　which　provides　a　new　way　to　prepare　high-performance　waterborne　polyurethane.　©　2023　Elsevier　Ltd