This paper presents the new technology and applications on microwave sensor for moisture content measurement. A dual-frequency microwave sensor based on circular microstrip antenna has been developed to measure moisture content(MC) of lossy liquids. The experiment is based on measurements of far-field reflection at two frequencies in the X-band,8.48 and 10.69GHz. Moisture content of the rubber latex samples can be determined with a standard error 0.49%.A prototype microwave based moisture sensor system suitable for the kiln drying of hardwood lumber has been developed. Using the prototype electronics and sensors, have obtained measurements of MC over the above MC range for red oak and yellow poplar with standard deviations of less than 1.5% MC at 4.5 to 6GHz.A smart active microwave sensor for measuring the moisture content of felts used in the paper milling industry and more generally of sheet-like materials is presented. An inversion procedure based on an Artificial Neural Network (ANN) approach is proposed in order to determine the moisture content of the felts. Finally the technical challenges and developing prospect of microwave sensors for Moisture Content Measurement are discussed.