The　carbide　characteristics　of　2.25Cr1Mo0.25V　steel　have　an　extremely　important　influence　on　the　mechanical　properties　of　welding　joints.　In　addition,　hydrogen　resistance　behavior　is　crucial　for　steel　applied　in　hydrogenation　reactors.　The　carbide　morphology　was　observed　by　scanning　electron　microscopy　(SEM)　and　the　carbide　microstructure　was　characterized　by　transmission　electron　microscopy　(TEM).　Tensile　and　impact　tests　were　carried　out　and　the　influence　of　carbides　on　properties　was　studied.　A　hydrogen　diffusion　test　was　carried　out,　and　the　hydrogen　brittleness　resistance　of　welding　metal　and　base　metal　was　studied　by　tensile　testing　of　hydrogenated　samples　to　evaluate　the　influence　of　hydrogen　on　the　mechanical　properties.　The　research　results　show　that　the　strength　of　the　welding　metal　was　slightly　higher　and　the　Charpy　impact　value　was　significantly　lower　compared　to　the　base　metal.　The　hydrogen　embrittlement　resistance　of　the　welding　metal　was　stronger　than　that　of　the　base　metal.　The　presence　of　more　carbides　and　inclusions　was　the　main　cause　of　the　decreased　impact　property　and　hydrogen　brittleness　resistance　of　the　welding　metal.　These　conclusions　have　certain　reference　value　for　designing　and　manufacturing　hydrogenation　reactors.　©　2021　by　the　authors.　Licensee　MDPI,　Basel,　Switzerland.