Abstract: By the characteristics of microwave radiation transfer, a microwave emissivity measuring meter is constructed. This equipment may be used to study the factors which have influence on microwave emissivity of the substance composed earth surface in an isolation condition. The microwave emissivity measuring meter consists of three parts radiometer, radiation chamber and sample box. In this paper, the principle of measurement, the reliability and accuracy of experiment and the stability of instrument were studied in lab. The results show that the characteristics of microwave emissivity measuring meter were satisfied. It is suitable for measuring the microwave emissivity of the substance composed earth surface. In this paper, the experimental results of microwave(λ=8.5 mm and λ=3.2 cm) emissivity of water and sand were shown and discussed.