Some efforts were done to reduce the autogenous shrinkage of cement paste by adding the superfine additive of limestone powder or fly ash. AC impedance techniques were used to study the autogenous shrinkage. The test results show that autogenous shrinkage increases along with the fineness increase of superfine slag. Silica fume also can increase the autogenous shrinkage. Largely mixing limestone powder or fly ash in cement paste with superfine slag can reduce autogenous shrinkage. It may be laid down as a rule that, as the autogenous shrinkage increases, the impedance becomes larger.