We　studied　linear　triblock　copolymer　and　homopolymer　mixtures　and　con-structed　a　new　Nakazawa-Ohta-type　model　to　describe　the　phase　separation　of　the　system.　For　this　high-order,　nonlocal　and　multicomponent　phase　field　system,　we　con-struct　two　second-order,　linear　and　energy-stable　schemes.　We　also　proved　the　energy　dissipation　and　mass　conservation　of　the　schemes.　Finally,　numerical　simulations　were　presented　in　the　3D　case,　which　verified　the　theoretical　analysis.　In　addition　to　those　reported　phase　structures,　we　found　some　new　ones,　which　can　give　some　guidance　to　experimenters.