The imaging methods in the field of ultrasonic phased array abide by the Rayleigh criterion and its resolution is limited by ultrasonic wavelength. The time reversal with multiple signal classification, termed TR-MUSIC(time reversal-multiple signal classification), has been introduced to improve the resolution and achieve super resolution imaging under the premise of keeping the ultrasonic working frequency unchanged and maintaining the detection depth of the system. The ultrasonic array data from the test object can be captured via full matrix capture process. Then the data was post-processed by plane B scan as well as TR-MUSIC to obtain the 2-D and 3-D ultrasonic images. The test object was assessed according to the imaging results. A block of steel with six 1mm-diameter side drilled holes, which can be considered as point-like targets, has been machined as the test object. Furthermore, the detection system of ultrasonic phased array has also been built. It is shown that TR-MUSIC can distinguish and locate these targets while the method of plane B scan fails. Therefore, the TR-MUSIC based on the theory of time reversal can increase the imaging resolution, and improve the quality of ultrasonic image.