This study evaluated the influence of silver nanoparticles (AgNPs) on evolutions of organic matter and nitrogen during co-composting of sewage sludge and agricultural waste. Two co-composting piles were conducted, one was treated without AgNPs (pile 1) and the other with AgNPs (pile 2). Results showed that the AgNPs affected the quality of final composts. Less organic matter (OM) losses were determined in pile 2 (57.96%) than pile 1 (61.66%). 27.22% and 30.1% of the initial total organic matter (TOC) was decomposed in pile 1 and pile 2, respectively. The final water soluble carbon (WSC) concentration in pile 2 was 23559.27 mg/kg DW compost which was significantly lower than pile 1 (25642.75 mg/kg DW compost). Changes of different forms of nitrogen in the two piles showed that AgNPs could reduce the losses of TN but increase the losses of mineral N. (C) 2017 Elsevier Ltd. All rights reserved.