Based on the basic principle of ultrasonic testing and the defect detection method, makes simulated tests on the quality defects of concrete filled steel tube(CFST). Applies the ultrasonic testing technique to detect a CFST arch bridge and proves the feasibility and correctness of the technique in CFST defect detection. Comparing to the trail results, inspects the detecting results by core-drilling method. It shows that the defects detected by ultrasonic testing are in good accordance with the drilling samples, which verifies the adaptability of the ultrasonic detection technique in the construction quality inspection of CFST structures and the correctness of the trail results.