In this study, the heavy metals in tannery sludge were solidified by using cement and power plant fly ash. Solidification characteristics were discussed with the compressive strength and chromium leaching characteristics of solids. The compressive strength of cement mortar was increased by the amount of fly ash up to 24.3~33.8%, which was considered the results of pozzolanic reaction. When the content of fly ash was 20%, cement mortar showed the highest value $295kg/ extrm{cm}^2$ for 28 days curing. At early curing days, solidified chromium tannery sludge solids were showed lower compressive strength because of the retard on the hydration of cement, but the compressive strength was recovered to be more than $140kg/ extrm{cm}^2$ for 28 days curing regardless with the amounts of fly ash. Also, the results of leaching tests by KSM and TCLP method were showed that the solidified chromium sludge have leached out 0.3~2.2% and 11~17%, respectively.