Abstract: Along with the rapid development of aviation and aerospace manufacturing technology, the application of sophisticated components is more and more widely. In the immersion ultrasonic C-scan testing of complex or large thickness, the multi-zone focus for different thickness of the testing area with the corresponding parameters is often applied. The developed four-channel immersion ultrasonic C-scan testing system and software CScanPro can achieve the multi-zone focus detection with four-channel simultaneous imaging scan, and can thus improve the detection efficiency. This software is practical, stable and user-friendly. CScanPro can also be applied to non-focused four-channel ultrasonic C-scan inspection, it is installed and used in three ultrasonic C-scan testing systems, and the test results are accurate to meet the test requirements.