Improving　system　capacity　is　always　a　hotspot　in　mobile　communication　systems.　As　an　important　space-time　code,　Vertical　Bell　lab　Layered　Space-Time　(V-BLAST)　code　detection　algorithm　has　attracted　much　attention　in　recent　years.　Sphere　Decoding　(SD)　is　comparable　to　ML　in　performance　and　much　better　than　traditional　detection　algorithm　of　V-BLAST　but　it　involves　much　more　complicated　computations.　An　improved　SD　algorithm　using　Genetic　Algorithm　(GA)　pre-searching　is　presented　in　this　paper　based　on　the　research　on　SD　search　route　and　GA　characteristic.　The　algorithm　tries　to　find　new　lattice　inside　of　sphere　by　trying　the　near　centre　lattice　based　on　GA　pre-searching　with　intrinsic　parallelism　and　heuristic　searching　therefore　effectively　reduces　the　complexity　of　SD.　©　2011　IEEE.