In view of the special working conditions and serious external interference of forging hydraulic press, the limitation of traditional method for detecting moving beam eccentricity is analyzed. According to the essential requirements of the detecting system, a new digital and non-contact method for detecting moving beam eccentricity is proposed. The basic principle and system composition are introduced in detail, in order to test the accuracy, linearity, anti-interference and long-distance signal transmission ability of the system, experiment study was made. The results of the experiment study shows that the sensor's precision is 10um, the linearity is less than 1%, and the system has a strong anti-interference ability, proof that the new method can be applied in moving beam eccentricity detection in forging hydraulic press's special working conditions. At last, some recommendations are proposed which is helpful in practical use.