The　objective　of　this　paper　is　to　use　the　age-layered　population　structure　model　to　increase　diversity　and　control　bloat　of　the　population　in　linear　genetic　programming.　Firstly,　we　use　two　level　tournament　selection　to　increase　the　sub-population　diversity　in　each　layer,　and　then　apply　the　new　model　to　linear　genetic　programming　to　increase　the　sub-population　and　the　entire　population　diversity.　The　age-layered　population　structure　model　segregates　individuals　into　different　age-layers　by　their　age,　so　it　limits　the　quantity　of　the　old　age　and　long　length　individuals.　Besides,　the　model　regularly　introduces　new　randomly　generated　short　individuals　into　the　youngest　layer　to　reduce　the　average　length　of　the　population.　The　experimental　results　show　that　the　age-layered　population　structure　model　can　increase　diversity　and　control　bloat　of　the　population　effectively.