This document specifies the method of contact pulse reflection ultrasonic inspection of steel ingots using longitudinal wave technology, including inspection personnel, ultrasonic instruments, probes and test blocks, inspection methods, quality levels and test reports. This document is applicable to the ultrasonic detection and classification method of the internal quality of smelting steel ingots such as electric arc furnaces, medium frequency induction furnaces, continuous casting billets and electroslag ingots. The detection types of internal defects in steel ingots are divided into core defects, segregation defects and subcutaneous defects.