With the increasing development of nanomaterials, silver nanoparticles (AgNPs) have become one of the most largely produced and most widely used artificial nanomaterials in global markets. Due to their excellent antimicrobial activity, AgNPs have been applied in a wide spectrum of fields, including industry, medicine and consumer products. Therefore, it is necessary to comprehensively understand the potential risks of AgNPs to environment and human health. Thus far, studies focusing on the safety of AgNPs have described the biological process of AgNPs in bodies, AgNPs-mediated effects and according molecular mechanisms. In this review, we systematically recapitulated recent findings on biological effects of AgNPs, including (1) general routs of AgNPs exposure to human bodies, as well as subsequent tissue distribution; (2) interactions with biological molecules of AgNPs in the body; (3) cellular uptake and mechanisms responsible for AgNPs-induced lethal effects. Moreover, we emphasized findings on environmental and health risks of AgNPs and corresponding mechanisms by which AgNPs exerted sublehtal effects under low concentrations. Additionally, we have a further outlook on the future studying in this field of AgNPs’ adverse effects.