Abstract: Long term wear and torsion will cause small-scale deformation of antenna pitch axis structure. The rapid and high-precision measurement of this deformation is of great value for the pointing accuracy correction of large aperture fully movable antenna and the health monitoring of pitch axis. In this paper, a single camera measurement system is built, a virtual camera mathematical model is established, and the structural deformation is transformed into spatial transformation for solution, so a rapid measurement method of pitch axis deformation is proposed. The experimental results show that the method can achieve an integrated accuracy of 0.2825 mm (rms) for the translation component and 0.2918° for the rotation component, and is capable of rapid measurement of 1mm scale deformation of the pitch axis. The system and its method have the advantages of non-contact, high precision and rapidity, and can meet the demand for long-term rapid measurements of the pitch axis of large-aperture, high-frequency radio telescopes with high accuracy, and are also applicable to the measurement of small deformations of other large structures.