Slump and compressive strength of the concrete with different steel slag powder content and different finenesses were discussed in this paper. It was indicated that: 1) High performance concrete with higher strength can be made using ground steel slag powder. 2) The greater content of steel slag powder, the more obvious was the effect of reducing slump losing. 3) About 40MPa concrete can be made using the steel slag powder whose specific surface was 510~600m2/kg under the condition that the content of steel slag powder was 50%~60%. 4) When the content of steel slag to be certain, the finenesses of steel slag powder had little effect on the performance of concrete.