A study on the method of estimating gasoline engine radiated noise by measuring surface vibration is carried out. Firstly, the theoretical basis and test method is studied. Then an experiment is carried out on a four-cylinder gasoline engine. By measuring the engine surface vibration velocity, the sound power level of these engine parts and of the engine body is calculated. The result shows that the estimation of engine radiated noise is accurate. It shows the sound power level of gasoline engine can be predicted by surface vibration.