The　1.3　μm　laser　source　has　a　wide　range　of　applications　in　the　fields　of　sodium　beacons,　optical　communication,　image　display　and　laser　medicine.　In　the　paper,　we　demonstrate　a　laser　with　an　LD　end-pumped　Nd:YAG　slab　crystal　hybrid　cavity　Innoslab　structure.　When　the　pump　power　is　high,　the　thermal　effect　of　the　laser　during　oscillation　has　an　impact　on　the　stability　of　the　resonant　cavity　and　the　quality　of　the　beam.　We　demonstrate　a　finite　element　model　of　an　Nd:YAG　crystal　by　means　of　heat　conduction　theory　and　analyse　the　effect　of　the　temperature　distribution　at　the　crystal　end　face　and　the　pump　spot　width　on　the　thermal　effect　of　the　crystal.　Calculations　show　that　the　finer　the　pump　spot,　the　more　pronounced　the　thermal　effect　of　the　crystal.　In　the　experiment,　the　Nd:YAG　slab　crystal　was　doped　at　a　concentration　of　1at%，and　a　mixing　cavity　is　constructed　with　a　concave　spherical　mirror　of　R1　=　1000　mm　and　a　convex　cylindrical　mirror　of　R2　=　900　mm;　the　length　of　the　cavity　is　55　mm;　a　negative　cylindrical　lens　of　Rc　=　-100　mm　is　inserted　in　the　cavity　as　a　compensating　mirror.　Finally,　the　maximum　output　power　in　the　resonant　cavity　without　the　compensating　mirror　was　46.9　W;　with　the　addition　of　the　compensating　mirror　the　maximum　output　power　was　40.5　W;　the　vertical　beam　quality　was　increased　from　2.98　to　1.28.　©　2023　SPIE.