Speckle interferometry is an efficiency method to analyze vibration. In certain conditions, this technique has some outstanding, and not need strict shook-proof condition, compared with the holographic method for measuring vibration. Therefore, it is suitable for analysis vibration with a large amplitude. Real-time interferometry is a rapid and simple method for measuring vibration of a body, it gives speckle pattern containing amplitude distribution of body-surface. By means of time-averaged method, the speckle pattern is recorded in fourier transform plane, or vibration lines are seen directly with eye, so analyzed efficiently amplitude, phase, and model of vibration. This paper deduces the intensity distribution function with real-time method, and gives experimental proofs of vibration body--the vibration lines with different frequencies, the last, the conclusion.