In this study, the possibility of the utilization of coal ash as earthwork materials is investigated. For this purpose, some laboratory experiments were carried out. The samples used in these tests are fly ash(FA), bottom ash(BA), coal ash dropped into ash pond(FA:BA=8:2), and mixed coal ash(FA:BA=5:5), which were discharged as a by-product at Yong-Yeul thermoelectric power plant, and general road filling materials. And for the deformation analysis of coal ash reclamation ground, several hyperbolic model parameters were determined by triaxial compression test. As a result of this study, coal ash has excellent engineering properties such as strength parameters comparing with general soils of the same grain size, especially in case of being used as backfill materials and reclamation materials on soft ground, and coal ash is superior to general earthwork materials in engineering properties becasuse of self hardening behaveiour, light weight property, etc.