For the performance of lime-fly-ash bound macadam, cracks often occur in the limefly-ash bound macadam base due to the dry-shrinkage and temperature-shrinkage during the stage of highway business. As a result, the service life of highway may be weakened. Because of the properties of its strength same as natural stone and the properties of expansion of steel slag, the study focuses on the change of dry shrinkage of the lime-fly-ash bound macadam after the fly-ash substituted by steel slag. Based on the test, the conclusion was driven that when the proportion of steel slag replacing the fly-ash is proper (ratio of steel slag and flyash is 1:2), it can weaken the dry shrinkage of mixtures.