An exploratory experiment is carried out for the abnormal sound caused by automobile transmission shaft.The experiment is made up of two parts:vehicle road-test and transmission shaft bench-test.Three evaluation indexes of vibration are observed in the bench-test,and they are coefficient of rotate speed fluctuation,vibration acceleration at intermediate support and radial displacement of the shaft.From the comparison and analysis results,the correlation between abnormal sound in cars and the evaluation indexes of automobile transmission shaft vibration is confirmed.Each index has different performances in evaluating abnormal sound caused by different problems.These conclusions will be of great significance in abnormal sound detection,optimal design and improving the production process of automotive transmission shaft.