We report for the first time the electrical transport in solid-state electrolyte nanowires. Single nanowire transport and in situ transmission electron microscopy studies show that Ag2Se nanowires can be high conducting orthorhombic beta-Ag2Se or low conducting cubic alpha-Ag2Se. It is also the first time that alpha-Ag2Se is found to be stable at room temperature. A threshold switching phenomenon exists in the low conducting alpha-Ag2Se with an on-off ratio up to 7 order magnitude. These results provide useful new information for exploring solid-state electrolyte nanowires as resistive switching memory devices.