Nanosilver is one of the most widely researched and applied nanomaterials. In recent years, in order to avoid toxic by-products in the synthesis of nanosilver, many studies have been done in the green synthesis of nanosilver. All kinds of natural compounds rich in plant tissues and microbial cells can complete the green synthesis of nanosilver, and the potential of nanosilver synthesis from different biological sources needs to be further explored. The controllability of the size and shape of nanosilver, as well as the reduction of migration and side effects under the premise of making nanosilver play an antibacterial role, are the next priorities. The mechanism and method of using plant, bacteria and fungal green synthesis of nanosilver are reviewed, the methods are analyzed and compared, the antibacterial performance, antibacterial mechanism and specific application of nanosilver are introduced, and suggestions are made for future development.