In　this　paper,　a　detector-aware　low-density　parity-check　(LDPC)　code　optimization　algorithm　is　proposed　for　the　ultra-high　density　magnetic　recording　channel,　such　as　bit-patterned　magnetic　recording　and　two-dimensional　magnetic　recording,　where　a　2-D　detector　(2D-DET)　is　employed　to　combat　2-D　intersymbol　interference　(2D-ISI)　effects,　by　acquiring　the　variance　of　the　2D-ISI　channel　log-likelihood　ratios　corresponding　to　the　specific　2D-DET.　The　new　parameter　builds　a　bridge　of　LDPC　code　optimization　between　the　ISI-channel　and　the　additive　white　Gaussian　noise　channel.　Numerical　results　show　that　our　proposed　algorithms　are　more　efficient　in　running　time　than　other　recently　proposed　optimization　algorithms.　Moreover,　the　protograph-based　quasi-cyclic　(QC)　codes　using　the　proposed　optimization　strategy,　which　have　a　low-complexity　QC　encoder　structure　with　an　effectual　parallelizable　protograph　decoder　composition,　enjoy　up　to　one　order　of　magnitude　performance　gain　in　bit　error　rate　over　the　other　random　codes　that　suffer　from　high　error　floors.　©　1965-2012　IEEE.