Abstract: In response to the measurement requirements of a large-scale arch dam chain 3D deformation measurement system, the technical specifications for inclination angle sensors were determined. A high-precision photoelectric inclination sensor scheme based on suspension wire was studied, which used incoherent collimated beams to form a measurement light field. The shadow spot of the suspension wire was amplified by an optical system to form a clear image and projected onto a linear charge coupled device (CCD). Based on the principle of spot position measurement, the displacement value of the shadow spot was obtained, and the tilt angle value of the measurement point was calculated in reverse. At the same time, in response to the long-term on-site operation requirements, a two-dimensional high-precision photoelectric inclination sensor structure was designed. Test results show that the resolution and range indicators meet the design requirements, achieving high-precision inclination measurement with a range of 3 093 seconds and an accuracy of 0.432 seconds.