As the most advantage measurement method nowadays, the Instantaneous Polarization (IP) measurement technology becomes one of the hot spots in the research field of polarimetric radar. Aiming at the measurement error of the traditional IP measurement technology, a new measurement method based on ambiguity function matrix is introduced. The measurement error caused by the nonorthogonality of the transmitting signals is eliminated by this method. The signal processing flowchart of the method is given. In order to resolve the problems involving the traditional polarization calibration technologies, such as implementation difficulty and low accuracy, the calibration method using single mental sphere is given. The availability of these methods is verified through the field test conducted by the IP radar system, KD-IPR.