Abstract: This paper discussed the influence of small addition of copper on the pro perttes and structure of WC-13% Fe/Co/Ni cemented carbide. The results of metallographic observation and microstructure investigation on it were described in detail by using SEM and TEM. Results show that copper has a role of refining and sphericizing WC grain. In case of about 0. 8% of copper addition, optimum properties of such alloy can be obtained with a bending strength of 2370 N/mm²,670N/mm² higher than that of alloy without copper addition. In addition,during the slow cooling process after sintering, a martensite transformation took place with a relation between martensite and γphase being in conformity with K-S orientation.