Abstract: There are some defects in the weld seams of flowmeter, such as incomplete fusion and penetration. There is a need of ultrasonic examination technique using pulse-A mode type ultrasonic testing. However, single probe cannot meet the needs of the examination because of the special structure of the inner flowmeters, and therefore several probes with different K values need to be used. The normal calculating process is labor consuming and easily leading to errors, so a simulation software of using visual studio and C++language is developed for the ultrasonic testing of flowmeter weld seam. It meets the requirements of screening out required probes with suitable K values by the software in an intuitive, high efficient and accurate way.