Abstract: HS1000 ultrasonic microscope is the old version of machine from SONIX. After scanning, the machine can not figure out the ROI area with complicated boundary except rectangular one. If the ROI background changed, the result would change a lot. Due to software inside machine was blocked, it was impossible to be upgraded. Utilizing vision software as platform, we developed new software for ultrasonic microscope. The new software can process facultative boundary of picture, and the error of calculation is within 1.6%. It proves that the new software is flexible to study and apply for different boundary and background of picture of welding interface.