A method for the determination of impedance of quartz crystal using automatic network analyzer electrical techniques is introduced in this paper. The vector network analyzer ENA 5070B which is produced by Agilent Company is taken to measure S parameters in short-circuit, open-circuit and crystal-circuit. The algorithm recommended in international standard IEC444-5 is based on theory of two-port S parameter transmission method and relationships between transmission admittance (Y21) and scattering parameters(S parameters). By data analysis, circuit symmetry is good. And around the resonance frequency, amplitude and phase of S parameters have obvious display the crystal characteristics. The phase is not zero on the resonance frequency because of lead inductance and parasitic capacity. The amplitude/phase-frequency curve of crystal impedance, which is in conformity with the stimulation of the crystal model, is achieved. By de-embedding process, high accuracy of series resonant frequency and the impedance around it are measured. Results have created favorable conditions for precisely determining the values of the electrical parameters of quartz crystal units.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.