A novel silver-organic conductive ink with no particles, consisting of silver–amide complex dispersed in glycol–water mixture, was developed in a simple way. The reaction mechanism during sintering was also studied and a multi-mechanism was found for the first time. Silver ions in solution can be reduced by glycol to metallic silver following the typical polyol process. Meanwhile, silver–amide complex will decompose to silver oxide, and is then immediately reduced by glycol. The result indicates that the silver oxide reduction mechanism plays a major role in the whole reaction. The type of amine has a great influence on the properties of the ink. When adding a proper amount of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), both the conductivity and adhesion of sintered silver film will be improved. Microstructures of the silver film were observed, and a multi-layered structure was detected. The relationships between structure and resistivity and adhesion were also researched. After being filled into a marker and drawn on polyimide (PI) film, the conductive ink was sintered at 150 °C for 1 hour using an oven, and the resistivity of the silver film was 18 μΩ cm, about 11 times that of bulk silver.