In　this　paper,　the　partner　selection　problem　with　a　due　date　constraint　in　virtual　enterprises　is　proved　to　be　an　NP-complete　problem.　So　it　cannot　have　any　polynomial　time　solution　algorithm　at　present.　A　nonlinear　integer　programming　model　for　this　problem　is　established.　The　objective　function　and　a　constraint　function　of　the　model　have　monotone　properties.　Based　on　the　above　observations,　a　Branch　&　Bound　algorithm　is　constructed　to　solve　the　problem.　Numerical　experiments　show　that　the　algorithm　is　efficient.　(c)　2005　Elsevier　Inc.　All　rights　reserved.