Phase-tilting interferometry for optical testing is proposed to retrieve the phase from interferograms with random phase tilts. The Radon transform is used to extract the tilted phase plane, and the phase distribution is retrieved by the least squares method. The proposed method has been applied to simulated and experimental interferograms, obtaining satisfactory results. The proposed method has high accuracy and good robustness, and it can be used for interferometric measurements in environmental vibrations. Additionally, it can be used for interferometers without a phase shifter to achieve high-precision analysis.