Thermal deformation will generate when lenses components in infrared optical system is in higher temperature environment. Especially over high temperature at local part, the surface shape and thickness of lenses will be changed and imaging quality will be influenced. For researching the thermal deformation of infrared optical lenses, quasi continuous laser with 1.06 μm wavelength is used to irradiate Germanium wafer to detect Germanium material deformation at different irradiation duration in real time. And the influence on imaging quality is researched. Obtained experimental data can provide references for lenses thermal deformation theoretical analysis.