The advantages of the optical fiber array point source generator relative to the lens array point source generator are analyzed. An optical path difference detection method based on Mach-Zehnder all-fiber interferometer and excess fraction method is proposed, which can measure the optical path difference of all beams relative to the beam emitted from central fiber. Meanwhile, the measurement influence of optical path difference on surface deviation calculation can be eliminated with introducing it into the mathematical model of tilted-wave-interferometry system. The results show that the measurement uncertainty of this detection system is 0.07λ3(λ3=632.8 nm). A parabolic mirror is measured with fiber array based tilted-wave-interferometry system and ZYGO interferometer, and the surface deviations obtained by the two interferometers are consistent.