The utility model discloses a special sample preparation tool for detecting lubricating grease by a spectrum analyzer, which belongs to the field of detection tools, and is characterized by comprisinga gun body, a mandrel, a top sleeve, a tension spring, a trigger and a disc electrode, the front end of the mandrel is provided with a disc electrode buckle matched with a disc electrode center hole.A tension spring is arranged between the positioning sleeve and the rear end of the top sleeve; the rear end of the mandrel penetrates through the rear end of the gun body and is exposed behind the gun body, and a knob is fixedly arranged at the rear end of the mandrel; the trigger is of a T-shaped structure, the middle of the trigger is hinged to the gun body, an arc-shaped rack is arranged at the upper end of the trigger, and a top sleeve rack meshed with the arc-shaped rack is arranged at the corresponding position below the top sleeve. Compared with the prior art, the method has the characteristics of high efficiency and reliability.