About　90%　of　the　world＇s　natural　gas　hydrates　(NGH)　exist　in　deep-sea　formations,　a　new　energy　source　with　great　potential　for　exploitation.　There　is　distance　from　the　threshold　of　commercial　exploitation　based　on　the　single　well　currently　used.　The　complex　structure　well　is　an　efficient　and　advanced　drilling　technology.　The　improvement　of　NGH　productivity　through　various　complex　structure　wells　is　unclear,　and　there　is　no　more　complete　combing.　Thus,　in　order　to　evaluate　their　gas　production　characteristics,　we　establish　a　mathematical　model　for　exploitation　of　NGH,　and　then　13　sets　of　numerical　models　based　on　the　geological　parameters　of　the　Nankai　Trough　in　Japan　are　developed　and　designed,　including　a　single　vertical　well,　a　single　horizontal　well,　1　similar　to　4　branch　vertical　wells,　1　similar　to　4　branch　horizontal　wells,　and　2　similar　to　4　branch　cluster　horizontal　wells.　The　research　results　indicate　that　wells　with　complex　structures　represented　by　directional　wells　and　multilateral　wells　can　significantly　increase　the　area　of　water　and　gas　discharge,　especially　cluster　wells,　whose　productivity　can　be　increased　by　up　to　2.2　times　compared　with　single　wells.　Complex　structural　wells　will　play　an　irreplaceable　role　in　the　future　industrialization　of　NGH.