In　this　paper,　we　investigate　the　mixed　initial-boundary　value　problem　with　large　BV　data　for　linearly　degenerate　quasilinear　hyperbolic　systems　of　diagonal　form　with　general　nonlinear　boundary　conditions　in　the　half　space　{(t,　x)　|　t　≥　0,　x　≥　0}.　As　the　result　in　[A.　Bressan,　Contractive　metrics　for　nonlinear　hyperbolic　systems,　Indiana　Univ.　Math.　J.　37　(1988)　409-421]　suggests　that　one　may　achieve　global　smoothness　even　if　the　C1　norm　of　the　initial　data　is　large,　we　prove　that,　if　the　C1　norm　and　the　BV　norm　of　the　initial　and　boundary　data　are　bounded　but　possibly　large,　then　the　solution　remains　C1　globally　in　time　and　possesses　uniformly　bounded　total　variation　in　x　for　all　t　≥　0.　As　an　application,　we　apply　the　result　to　the　system　describing　the　motion　of　relativistic　closed　strings　in　the　Minkowski　space　R1　+　n.　©　2009　Elsevier　Inc.　All　rights　reserved.