Laser ultrasonic (LU) three-dimensional (3D) imaging system combining wavelet threshold method (WTM) is presented, in which a laser beam is as a scanner and an interferometer is as a receiver.The ultrasonic signals saved are processed by wavelet threshold for reducing noise.Then, the data processed constitutes a 3D matrix in the scanning sequence, which could reconstruct the object model of aluminum block with artificial defects using MATLAB procedure.And defects inside the sample can be imaged and visualized.The results show that 3D ultrasonic imaging is a novel technique to reconstruct object model for visualizing damages or flaws inside the materials.