Icing velocity sensor is an important component to protect aircraft flight under icing conditions. The icing velocity sensor based on infrared spectrum absorption is more precise than others and was studied in this paper. The theoretical model of ice thickness measurement using double contrast wavelength absorption method was deduced. An icing velocity sensor based on the infrared spectrum absorption was designed, in which two infrared laser diodes driven by pulse circuit were used. The key technologies of the icing velocity sensor based on infrared spectrum absorption were proposed, along with solutions. The study provides a reference for the practical application of the infrared icing velocity sensor.