The　effects　of　Er　addition　on　microstructural　refinement　and　oxidation　resistance　of　Ti-46Al-8Nb　alloys　were　studied.　The　alloys　were　prepared　by　the　cold　crucible　induction　levitation　melting　method.　The　optical　microscopy,　SEM　and　TEM　observation　showed　that　Er　refines　the　microstructure　of　Ti-46A1-8Nb　alloys.　The　cyclic　oxidation　behavior　experiment　was　done　in　air　at　900°C　up　to　one　hundred　times.　Based　on　the　oxidation　kinetic　analysis　and　the　phase　constitution,　microstructure　and　the　interface　of　the　oxidation　scale　and　the　matrix　were　investigated　by　means　of　XRD　and　SEM　equipped　with　EDS,　the　cyclic　oxidation　resistance　of　TiAl　based　alloys　was　explored.　The　results　showed　that　no　spallation　of　layer　occurs　in　both　alloys,　and　Ti-46Al-8Nb-0.1Er　comparing　with　Ti-46Al-8Nb　exhibits　more　excellent　oxidation　resistance,　oxides　formed　on　the　surface　consist　of　mainly　Al2O3,　the　continuous　compact　oxidation　scale　with　a　good　combination　with　the　matrix　significantly　decreases　the　oxidation　rate,　the　mass　gain　and　the　oxide　scale　thickness.　The　addition　of　Er　purifies　the　alloy　matrix　and　prevents　the　inward　diffusion　of　oxygen　atoms,　thereby　improves　the　cyclic　oxidation　resistance　of　TiAl　based　alloy.