Abstract: With the development of vacuum application industry, because of its superior technical skills, the new composite vacuum gauge is playing a more and more important role in the field of vacuum measurement. Due to its modular design, laboratory calibration methods have been unable to carry out routine calibration. Based on the analysis of the principle of magnetron cold Pirani vacuum gauge to measure the composite, log variable output analog signal is changed into standard voltage signal of the vacuum degree, error analysis is carried out, and calibration results is obtained. This technology provides the experimental basis and theoretical basis for the calibration of the vacuum gauge, and solves the problem of daily calibration of this vacuum gauge.