NbSi2 coating was prepared on the surface of Nb substrate. The high temperature oxidation behavior of NbSi2 coating samples at 1 200 ℃ and 1 450 ℃ in air was studied, microstructures and phase compositions of the coating were further analyzed by scanning election microscopy( SEM) and X⁃ray diffraction ( XRD) . The results demonstrated that NbSi2 coating was dense and uniform, composed of NbSi2 phase and a small amount of Nb5 Si3 phase. During the oxidation of 1 200 ℃ in air, small particles of Nb2 O5 was formed which caused no block to the liquidity of SiO2 but distributed uniformly in SiO2, to form a dense oxide film on the surface of NbSi2 coating. So NbSi2 coating could protect Nb substrate from oxidation at 1 200 ℃ in air for 120 h and that of mass gain was only 7. 42 mg. cm-2 . The coating exhibited good oxidation resistance at 1 200 ℃ due to Nb2 O5 particles While the poorly oxidation resistance of NbSi2 coating at 1450℃ was attributed to big particles of Nb2 O5 produced at 1450℃, which blocked off the flow of SiO2 to form loose and porous oxide film.%在金属铌表面制备NbSi2涂层，采用SEM和XRD分析涂层的微观结构和物相组成，研究了涂层样品在1200℃和1450℃大气环境下的氧化行为．结果表明： NbSi2涂层致密均匀，以NbSi2为主相，含少量Nb5 Si3相；1200℃氧化时，由于生成的小颗粒Nb2 O5不影响SiO2的流动性，其弥散分布于SiO2中而形成连续致密的氧化层，有效阻隔了氧的入侵，抗氧化时间可达120 h，其单位增加质量为7．42 mg · cm－2；1450℃氧化时，由于生成粗大颗粒的Nb2 O5阻碍了SiO2的流动，氧化层疏松多孔，抗氧化性能较差．
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