Abstract: The article mainly introduces the results of fatigue test of 209 welded frame.It illustrates that the ket element to the design of welded frame of reciprocating action loading is welded joint.If horizontal welds exist in bottom plate and high tensile stress acts on the frame,its fatigue strength can not be guaranted.Welding position,joint type and technological method all have great influence upon fatigue strength.In this article,the results of vibration treatment and heat treatment are compared.It shows that viberation ageing treatment can increase 20% fatigue life of the frame.Vibration ageing treatment not only has activemea nings of increasing fatigue life,but also has notable economical benefit.