Producing　oligodextran　with　an　enzymatic　membrane　reactor　(EMR)　is　a　promising　alternative　to　traditional　fermentation　processes　due　to　its　high　efficiency　and　environmental　compatibility.　Process　analysis　and　optimization　of　an　EMR　system　used　for　producing　oligodextran　are　critical　to　improving　EMR　operating　stability　and　cost　effectiveness.　We　herein　developed　a　mathematical　model　to　evaluate　the　effects　of　operating　conditions　and　membrane　properties　on　the　reaction-separation　behavior　of　an　EMR.　Our　analysis　shows　that　tailoring　a　membrane　with　large　porosity　and　uniform　pore　size　distribution　can　simultaneously　improve　the　product　quality　and　production　efficiency.　The　optimal　parameters　of　operating　pressure　and　agitation　speed　for　achieving　high　production　efficiency　depend　on　the　selection　of　operating　mode.　EMR　prefers　higher　operating　pressure　to　increase　the　production　efficiency　under　water　feeding　mode.　However,　since　the　membrane　suffered　severer　fouling　under　substrate　feeding　mode,　the　extensive　agitation　is　required　to　inhibit　membrane　fouling　and　enhance　production　yield.　Our　work　paves　a　new　avenue　towards　the　fundamental　understanding　and　designing　of　highly　effective　and　low　consumptive　EMR　for　oligodextran　production.　©　2021　Elsevier　B.V.