The vibro-cutting as a new method of machining has attracted increasing attention and has been successfully used for precise and ultraprecise cutting in the United States and Japan. A precise vibro-threading device on the lathe for use in threading female screw with small dimension developped by the author in terms of the principle of ultrasonic vibration has been introduced in this article. It is verifiable that this device is efficient for improving the accuracy and roughnees of the surface of the thread.