A　key　challenge　facing　developing　countries　is　how　to　promote　export　performance　through　trade　liberalization　(TL).　Using　large　and　highly　disaggregate　firm-level　data　with　6-digit　HS　categories　for　1995–2019,　we　investigate　the　issue　for　China　based　on　the　recent　literature　of　export　margins　(XM).　Export　growth　is　decomposed　into　extensive　and　intensive　margins　(EM　and　IM),　and　IM　further　into　price　and　quantity　margins　(PM　and　QM).　We　develop　three　empirical　hypotheses　based　on　a　theoretical　model　that　includes　external　economies　of　scale　(EES)　and　industrial　agglomeration　(IA)　as　well　as　TL-XM　links.　Then　we　take　China＇s　entry　to　World　Trade　Organization　(WTO)　in　2001　as　a　quasi-natural　experiment　in　difference-in-difference　(DID)　regressions.　The　estimate　results　suggest　that　TL　increases　both　EM　and　IM　(and　QM)　but　reduces　PM　after　China＇s　entry　to　TWO　in　2001.　The　finding　is　robust　to　various　specifications　of　the　empirical　model　and　measurements　of　the　variables.　The　further　estimations　show　significantly　positive　effects　of　EES,　IA,　and　their　interactive　terms　with　TL　on　EM,　IM,　and　QM.　The　positive　effects　are　larger　for　medium-tech　industries　than　low-tech　and　high-tech　industries.　©　2024　The　Author(s)