Rapid synthesis of silver nanowires (Ag NWs) with high quality and a broad processing window is challenging because of the low selectivity of the formation of multiply twinned particles at the nucleation stage for subsequent Ag NWs growth. Herein we report a systematic study of the water-involved heterogeneous nucleation of Ag NWs with high rate (less than 20 min) in a simple and scalable preparation method. Using glycerol as a reducing agent and a solvent with a high boiling point, the reaction is rapidly heated to 210 °C in air to synthesize Ag NWs with a very high yield in gram level. It is noted that the addition of a small dose of water plays a key role for obtaining highly pure Ag NWs in high yield, and the optimal water/glycerol ratio is 0.25%. After investigating a series of forming factors including reaction temperature and dose of catalysts, the formation kinetics and mechanism of the Ag NWs are proposed. Compared to other preparation methods, our strategy is simple and reproducible. These Ag NWs show a strong Raman enhancement effect for organic molecules on their surface.