In　this　work,　the　structural,　mechanical,　electronic　and　optical　properties　of　Be3X2　(X　=　N,　P,　As)　were　studied　using　first-principles　calculations.　Structural　parameters　of　Be3N2　and　Be3P2　agree　well　with　their　experimental　values.　The　calculated　band　gap　of　Be3N2　is　in　good　agreement　with　the　available　experimental　value.　Moreover,　the　calculated　results　show　that　three　compounds　are　found　to　have　direct　band　gaps.　The　band　gaps　of　Be3P2　and　Be3N2　are　1.12　and　0.92　eV,　respectively,　which　are　potential　candidate　materials　for　solar　absorber　applications.　Moreover,　the　band　gap　of　Be3P2　can　be　tuned　from　0.70　to　1.40　eV　by　applying　the　hydrostatic　strain.　Be3P2　and　Be3N2　exhibit　strong　and　wide　optical　absorption　in　the　light　spectrum.　The　elastic　constants　and　moduli　were　studied　for　the　first　time,　and　the　results　imply　that　all　compounds　are　brittle　materials.　Our　work　is　helpful　to　explore　potential　materials　for　applications　in　optoelectronic　devices.