Ruturaj Gavali
Ansys Employee

Hey Yang Guorui!

Please refer to this example problem. The model here includes piezoelectric material definition. 

Chapter 39: Wire Bonding Ultrasonic Transducer (ansys.com)

Also, refer to the link below to understand how to create new materials and define their properties.

Material Data (ansys.com)

Thanks!

For more information, check out the following links:

Ansys Help

Ansys Learning Forum (Rules & Guidelines)