Sludge is obtained from the wastewater treatment processing, has not been currently paid attention as much as the other solid wastes such as municipal and industrial solid waste in Vietnam. This research has been focused on evaluating the composition of sludge. The sludge from 3 wastewater treatment plants (WWTPs) in Hanoi was used in this study. The content of nitrogen and phosphorus were found to be 4-7 percent Nand 2-4 percent P dry weight meaning that in 1 ton of dry sludge equal 85-150 kg of urea fertilizer and 250-500 kg of single supephosphate fertilizer. In addition, sludge also contained the nutrients such as macro elements (K, Ca, Mg, S) and micro elements (Fe, Mn, Cu, Zn) which are necessary for the growth of plant. The sludge containing heavy metals such as Cu, Zn, As, Cr, Cd, Hg and Pb were found in the range of allowable limit following US standard for production of fertilizer. The sludge seems to be as a rich multi-nutrient source for composting.