The invention relates to a silver base cadmium-free medium temperature solder and a preparation method thereof, which overcomes the defects of high cost of cadmium-free silver base solder, poor technical indicators of melting temperature and range, high brittleness, and narrow application range due to difficulty in machining into soldering wire. The silver base cadmium-free medium temperature solder comprises silver, copper cathodes, zinc, tin, copper-phosphorus alloy, manganese, zirconium, copper foil and lanthanum; or nickel, silver, copper cathodes, zinc, tin, copper-phosphorus alloy, manganese, zirconium, copper foil and lanthanum. The preparation method of the silver base cadmium-free medium temperature solder comprises the following steps: feeding, warming up, cooling and discharging, casting, and extruding to obtain the silver base cadmium-free medium temperature solder. The solder has the advantages of no cadmium, low content of silver, and good welding performance.