Point diffraction interferometry is a method for the detection of super-precision surface shape of optical components. This method uses micron-scale hole diffraction to generate nearly ideal spherical wave as the reference surface, which gets rid of the reference mirror's limitation on the accuracy of traditional interferometry. If the interference technology based on point diffraction can be extended to the field of three-dimensional measurement, it will be expected to provide a new way for ultra-high precision three-dimensional measurement. In order to solve the problem of non-destructive measurement of three-dimensional topography of complex curved surfaces in small areas, a three-dimensional topography measurement method based on point diffraction interference technology is proposed. The high-precision point diffraction interference fringes are generated by double optical fibers, and the fringes are projected on the surface of the measured object. The piezoelectric ceramic phase shifter drives the mirror to generate phase shift, and seven interference images with different phase shift are obtained on the CCD detector. By collecting and processing the deformed interference fringes modulated by the height information of the measured object, the three-dimensional topography information of the measured object is recovered. A specific three-dimensional measurement optical path scheme of point diffraction interference fringe projection based on phase-shifting of double fiber splitting path is proposed, and the phase-height recovery mathematical model of the measurement system is constructed. Based on the simulation of seven-step phase-shifting projection interference fringes, the interference image processing algorithm is studied, which mainly includes interference image preprocessing, edge detection, edge extraction, phase extraction, branch-cut phase unwrapping and phase-height information restoration based on the continuous phase information distribution obtained by unwrapping. The system structure parameters are calibrated. According to the relationship between the pixel coordinates of the camera image and the world coordinates, Zhang Zhengyou camera calibration is used to calibrate the camera parameters. Based on the lens imaging principle and the mathematical relationship of the projection system, the specific calibration algorithm formula is derived. By using the electronically controlled displacement table and the corner detection method, the distance from the optical center of the camera lens to the reference plane and the central projection angleof the optical fiber projection end are calibrated respectively. Based on an optical fiber with a core diameter of 4 μm and a core distance of 120 μm, an actual point diffraction interference three-dimensional topography measurement experimental system was built. The three-dimensional topography of a hemispherical plaster model with a diameter of about 40 mm was measured six times repeatedly. The average height of the center of the measured object is 19.280 1 mm. Finally, to verify the feasibility and correctness of the proposed method, the measurement results of the system are compared with those of the ATOS Compact Scan commercial three-dimensional scanner of GOM company in Germany. The experimental results show that the difference between the arithmetic mean value of the center height of the two measurement methods is only 0.000 2 mm, which verifies the correctness and reliability of the experimental system. The standard deviation of the center height measurement results of the point diffraction interference three-dimensional topography measurement system is 0.001 3 mm, which verifies that the experimental system is feasible and stable. The proposed system integrates point diffraction interferometry with three-dimensional measurement technology, offering advantages such as high precision and non-destructive measurement, while featuring a simple principle and ease of implementation. The research results effectively realize high-precision three-dimensional shape measurement, which can provide theoretical reference for the extended application of point diffraction interference technology in the field of three-dimensional shape measurement.