Owing to an increased application of novel light sources such as ultra-short and ultra-intense free electron lasers （FEL）， damage resistance of extreme ultraviolet （EUV） and X-ray thin-film mirrors has attracted wide attention. This paper introduces a nanosecond EUV damage instrument manufactured by the Institute of Precision Optical Engineering （IPOE）. EUV damage tests were conducted on boron carbide （B₄C） reflective mirrors， gold （Au） and ruthenium （Ru） metal monolayer mirrors， B₄C/Ru bilayer mirrors commonly used in EUV and X-ray free electron lasers， and molybdenum-silicon （Mo/Si） multilayer mirrors used in EUV lithography. Damage resistances for thin-film mirrors with different optical materials and structures were determined. Combined with theoretical simulations， damage mechanisms such as thermal melting， thermal stress， and interlayer diffusion-reaction were detected.