With　the　rapid　update　of　internet　hardware　and　software,　especially　the　rise　of　mobile　internet　and　cloud　computing　platforms,　web-based　sites　has　become　the　world＇s　largest　source　of　information,　and　so　how　to　extract　the　accurate　domain-specific　knowledge,　how　to　improve　the　extraction　efficiency　and　how　to　save　the　cost　during　information　harvest　have　become　the　hot　research　spot.　With　the　advantage　of　the　theories　and　techniques　of　software　architecture,　the　paper　presents　a　web　knowledge　discovery　model　based　on　SOA　and　cloud　computing,　through　which　valid　information　can　be　obtained　in　an　automatic　or　semi-automatic　way　from　the　distributed　information　sources　environment.　A　unique　web　information　extraction　system　built　base　on　the　architecture　and　the　verification　results　were　given　in　the　final　chapter.　©　2012　IEEE.