Angle measurement, as a pivotal technology in the field of precision metrology, holds significant application value in modern industries, such as aerospace, equipment manufacturing, and high-precision inspection. To address the challenge of high-precision small-angle measurement in the precision manufacturing and assembly of large-diameter components such as large gears, this article proposes an extended-field-of-view high-precision rotation angle measurement method based on binocular vision collaboration. Firstly, an improved two-dimensional four-parameter coordinate transformation algorithm is employed to formulate a calibration model for the measurement reference plate, achieving high-precision calibration and providing a reliable reference basis for angle measurement. Secondly, to overcome the limited field of view of a single camera when measuring large-scale workpieces, a binocular vision measurement system with complementary spatial fields of view is established. A feature point matching-based algorithm for solving the field-of-view center coordinates is proposed, enabling the determination of the camera′s field-of-view center coordinates in the measurement reference plate coordinate system. Thereby, a theoretical foundation for angle measurement is achieved. Finally, based on the aforementioned methods, a binocular vision-based rotation angle measurement system is developed. A large gear with a modulus of 20 mm and 30 teeth is used as the test object. Systematic accuracy tests and repeatability verification are conducted within a rotation range of 0° to 20°. The results show that the system achieves an absolute measurement accuracy of 6″ and a repeatability accuracy of 5″, demonstrating high measurement precision and stability. The proposed method and the designed system meet the requirements for high-precision dynamic angle measurement of large-diameter components, providing a new technical approach for such applications.