An　efficient　modified　leapfrog　time-marching　scheme　for　the　diblock　copolymer　model　is　investigated　in　this　paper.　The　proposed　scheme　offers　three　main　advantages.　Firstly,　it　is　linear　in　time,　requiring　only　a　linear　algebra　system　to　be　solved　at　each　time-marching　step.　This　leads　to　a　significant　reduction　in　computational　cost　compared　to　other　methods.　Secondly,　the　scheme　ensures　unconditional　energy　stability,　allowing　for　a　large　time　step　to　be　used　without　compromising　solution　stability.　Thirdly,　the　existence　and　uniqueness　of　the　numerical　solution　at　each　time　step　is　rigorously　proven,　ensuring　the　reliability　and　accuracy　of　the　method.　A　numerical　example　is　also　included　to　demonstrate　and　validate　the　proposed　algorithm,　showing　its　accuracy　and　efficiency　in　practical　applications.