Abstract: Calcium and magnesium contents of sludge composting are measured by using the method of ammonium acetate-EDTA complex metric titration here, through Fermentation accelerant and increased nutrient agent treatments. The results showed as following: 1, exchangeable Ca and Mg contents of sludge single treatment increased more 6.83% and5.12% at the end of composting, than at the beginning of composting. 2, Fermentation accelerant added in sludge from 8% to 40%,,the exchangeable calcium and magnesium are more 4.38% ~ 10.58% and 6.77% ~ 13.78% at the end of composting than at the beginning of composting. The exchangeable Ca increased 19.51% ~ 104.83%, but 6.05% of a decreased trend for exchangeable magnesium, Compared with the sludge single compost. 3, as increasing the amount of nutrient agent from 30% to 50%, the exchangeable calcium and magnesium are more 3.88%~7.75%and 5.24%~9.18% at the end of composting than at the beginning of composting. The exchangeable Ca increased in 11.35%~41.13%,but 49%~-3.96% of a decreased trend for exchangeable magnesium, Compared with the sludge single compost. 4, under the condition added 24% of the Fermentation accelerant agent to the sludge, as the Increased nutrient agents from 8% to 32%, the exchangeable calcium and magnesium measured are increased 2.63%~5.54%and3.6%~4.19% at the end of composting , compared with The beginning of composting. The exchangeable Ca increased in 52.34%~112.04%,but -10.15%~-15.59% for exchangeable magnesium, Compared with the sludge single compost.