Abstract: By means of nondestructive testing,metallographic examination,SEM (EDS) analysis,the abnormal tracks on small forged pieces made by 0Cr17Ni4Cu4Nb steel have been analyzed. The result indicates that there exists fine strip inclusions which conforming to manufacturering standard (i.e. national standard) but not conforming to the performance requirements of the part. Through the analysis and evaluation of the raw material and forging,the controlling method of the fine strip inclusions in precipitation-hardening stainless steel have been discovered,and extra inspection method has been proposed to evaluate these fine strip inclusions.