Abstract: PtIrRu alloy plate is a new function material which has just been researched. The requirement for its quality is special strict since it is used in the motor of aeroplane. There has not been a standard method of ultrasonic testing for PtIrRu alloy thin plate so far. The method of ultrasonic testing for PtIrRu alloy thin plate with Lamb wave is introduced in the paper. The method of ultrasonic testing for other new plate material can refer it.