A　one-dimensional　and　two-dimensional　combined　computational　model　(1-D　and　2-DCC　model)　was　set　up　to　simulate　the　performances　of　the　basic　type,　orifice　type　and　double　inlet　type　pulse　tube　refrigerators　(PTRs).　The　Darcy-Brinkman-Forchheimer　model　and　the　thermally　non-equilibrium　model　were　adopted　to　depict　the　flow　and　heat　transfer　in　the　regenerator　which　was　modeled　by　taking　the　mesh　as　a　porous　medium.　Parameter　communicating　algorithms　were　defined　to　calculate　velocity　and　temperature　at　the　junctions　between　the　1-D　and　2-D　computational　regions.　Then　the　simulation　codes　for　the　whole　PTRs　were　developed.　The　working　process　and　complex　flow　phenomena　such　as　velocity　and　temperature　annular　effects　and　DC　flow　in　PTRs　were　revealed.　The　results　show　that　a　close　loop　in　the　PTR　can　be　formed　by　using　a　double-inlet　valve　which　leads　to　the　occurrence　of　DC　flow.　For　the　case　studied,　the　DC　flow　rate　accounts　for　4.66%　of　the　total　mass　flow　rate　under　the　present　parameters　and　working　conditions.