The experimental instrument and method for measuring thermal conductivity of materials were introduced in this work．The instrument，which is based on the steady-state plate principle，uses electric energy and solar energy as dual energy sources to measure the thermal conductivity of various materials such as metals，nonmetals，liquids，and gases etc．The experimental instrument has the characteristics of rail plug-in structure，stable，safe，easy to operate，wide measurement content，accurate measurement data，and can be used in scientific research and physics experimental teaching field．