Abstract: This paper analyzes the removal of surface defects of zirconium alloy tube before and after pickling, and studies the effect of pickling on ultrasonic detection. Analytical studies have shown that proper pickling processes can eliminate the small defects in the surface of zirconium alloy tube and improve the surface quality of the tube. But pickling cannot completely eliminate the crack defects in the tubes, and it may affect the ultrasonic reflection by defects, and even cause defects undetected.