Design　optimization　of　the　solar　heating　and　hot　water　system　used　in　the　Inner　Mongolia　region　was　studied　in　this　paper.　The　dynamic　heat　load　of　the　building　was　calculated　based　on　DEST,　and　the　characteristics　of　heating　load　and　hot　water　load　of　the　system　were　analyzed.　Associated　with　the　characteristics　of　the　dynamic　solar　radiation　of　the　Inner　Mongolia,　the　design　optimization　was　proposed.　In　addition,　the　economical　analysis　of　the　system　was　carried　out.　Under　this　design　condition,　solar　heating　and　hot　water　system　can　undertake　20.26%　of　the　heating　load　in　winter　and　61.74%　of　the　hot　water　load　in　summer.　The　investment　recovery　period　is　5.34　years　and　879,547RMB　can　be　saved　during　the　lifetime　of　the　system.