In this paper, a comprehensive experimental investigation on the surface roughness of metal kerf in abrasive waterjet cutting metal material is presented. Orthogonal experimental design method and analysis of variance are utilized in researching the effects of processing parameters on the roughness of smooth zone. By analyzing, it could be concluded that lower waterjet pressure, smaller cutting speed and abrasive grit, larger abrasive flow rate and appropriate standoff are favorable to generate smooth metal kerf. A verification experiment was conducted using an optimizing cutting condition. The result indicates that the surface roughness of metal kerf has been improved effectively.