The mechanical characteristics and extremely hard working conditions of large die hydraulic press are considered. The limitations of traditional condition monitoring method are analyzed. A new condition monitoring system which consists of a digital and non-contact method for measuring column stress and a digital method for measuring moving beam’s spatial altitude based on machine vision is proposed. The basic principle and composition of the system are introduced in detail. The system is applied in 300MN large forging hydraulic press, and large amounts of monitoring data are collected. Data analysis is carried out. The laws of column stress distribution in different working conditions are found out. At last, some recommendations are proposed which is helpful for the safety operation and maintenance of large hydraulic press.