Composites of nano silver on magnetic carbon (Ag-Fe3O4/C) were facilely prepared by in-situ reduction of Tollen's reagent. The prepared sample was characterized and compared with a control sample obtained from AgNO3. The results showed that the Ag-Fe3O4/C sample obtained from Tollen's reagent as the silver source had better degree of crystallinity, smaller size and more Ag loading amount than that of the control sample. The reason of these advantages was discussed base on the in-situ loading mechanism. Then the prepared sample and the control sample were used in the reduction of Rhodamine B, the prepared sample also showed better performance in the catalytic application. It was suggested that using Tollen's reagent as the silver source could improve the economics of the Ag nanocomposites on their preparation and further application. (C) 2017 Elsevier B.V. All rights reserved.