The invention discloses a bar cutting tool life prediction method. The wearing capacity in each time of cutting is obtained by conducting quantitative detection on the wearing capacity of the side face of a movable tool, then the predicted life of a bar cutting tool is obtained according to the difference between the failure spacing distance and the initial spacing distance between a fixed tool and the movable tool, that is to say, the bar cutting tool life prediction method can achieve the technical purpose of obtaining the service life of the tool in the design stage, and the reliability ofthe cutting machine property is improved. Particularly, the bar cutting tool life prediction method has the following advantages that firstly, a full life test does not need to be conducted on the tool, and the characteristics of being low in economical cost, high in prediction speed and high in accuracy are achieved; secondly, a prediction result better conforms to an actual result, and the toollife prediction error is small; and thirdly, the tool life is predicted through the method, the tool can be replaced in advance, the condition that the blank machining quality is influenced due to thefact that the tool is damaged is prevented, and the reliability of a bar cutting machine is improved.