The study on the differential diagnosis in 47 cases of primary hepatocarcinoma (PH) and 36 cases of metastatic hepatocarcinoma (MH) was performed with the real time B mode ultrasonic scanner. The pathological identifica­tions had been made before the ultrasonic scanning. The ultrasonic features seen in PH and MH were as follows: 1, Sound halo was found in 38/47 (80.9%) of PH and 14/36 (38.7%) of MH. 2, The margin was irregular in 33/47 (70.2%) of PH and regular in 30/36 (83.3%) of MH. 3, The echo of the posterior wall was strengthened or no change in 37/47 (78.7%) of PH and weakened in 30/36 (80.3%) of MH. 4, There was silhouette in 35/47 (74.5%) of PH and 10/36 (27.8%) of MH. 5, The focus was single in PH, accounting for 66% (31/47) and multiple in MH 86.6% (31/36). The diameter of the focusoem (strong echo) was found in 11/14 (78.6%) of MH, while the diameter > 3cm (strong echo) was found in 18/21 of PH, being 85.7%. As to the ultrasonogram of the gall bladder, some changes of enlargement, calculus, thickened wall 4mm and unclear margin were observed in 18 of 31 cases of PH, while in cases of MH, only 2 revealed unclear margin of the gall bladder, about which the inner relationship between PH and MH needs further study. It is concluded that the accurate use of digital handling function aids in detecting the margin of the focus, the structure of inner echo and the correlation with peripheral contour, raising the accuracy rate of diagnosis. The index of the differential diagnosis identitied by experiment is provided.