Studies on exact measuring methods of stress wave velocity with modern electron-ic technology;the relationship among modules of elasticity with density and stress wave ve-locity of materials tested;the correlativity between stress wave and destructive testing ac-cording to relevant Chinese National Standard in force were conducted.The research resultsindicated that the bending modules of elasticity measured by non-destructive testing of stresswave was precise enough and it was possible to develop online quality control system of MDFaccording to mechanical properties and automatic control system of production line.