The　Er3+/Yb3+,　Er3+/Nd3+　and　Er3+/Dy3+　co-doped　BaLaGa3O7　crystals　were　grown　by　the　Czochralski　method.　The　absorption　spectra,　up-conversion　emission　spectra,　near-infrared　and　mid-infrared　emission　spectra,　as　well　as　the　fluorescence　decay　curves　of　them　were　measured　at　room　temperature.　Detailed　spectroscopic　analyses　were　carried　out　and　the　spectral　parameters　of　them　were　compared.　Furthermore,　the　energy　transfer　processes　among　Er3+-Yb3+,　Er3+-Nd3+　and　Er3+-Dy3+　were　investigated　and　the　rate-equation　theory　models　were　built　and　discussed.　The　results　demonstrate　that　Er/Nd:　BaLaGa3O7　crystal　is　a　best　candidate　for　obtainment　of　~2.7　µm　laser　among　the　three　doping　kinds,　since　the　introduction　of　Nd3+　not　only　increases　the　absorption　efficiency　of　pump　energy,　but　also　inhibits　the　self-termination　bottleneck　effect,　which　are　both　beneficial　to　the　output　of　the　mid-infrared　~2.7　µm　laser.　©　2018