Abstract: In the 1980s, phased array ultrasonic testing was transferred from the medical field to the industrial field, and this technology has developed rapidly in areas such as pressure vessels, large forged shafts, steam turbine components, and oil and gas pipelines. At the same time, it requires high theoretical knowledge from inspectors (process developers), who need a deeper understanding of aspects such as sound field focusing and near-field zones. This article conducted detection tests on test blocks and welds using different numbers of excited elements at different focal depths, and analyzed the impact of different numbers of excited elements on weld inspection results, to provide process reference for peers.