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The precision of machining equipment is the main factor that affects the reliability of the manufacturing system. The failure of equipment function which affects the efficiency of manufacturing system is often caused by out-of-tolerance of precision. In this research, the precision degradation was connected to the stress and frequency of the external load, and a method was proposed to predict the precision retention time (PRT) of machining equipment, in which the traditional fatigue theory was combined with the monitoring technology of the operating vibration information. The calculation method of vibration energy was derived based on the principle of mechanical dynamics. Combined with signal processing technology, the complex loads were expressed by energy spectrum in frequency domain. According to the characteristics of S-N curve and the historical test data, the F-E-T surface reflecting the relationship among load frequency, vibration energy and precision retention time was obtained. The surface was used to predict the PRT of the equipment under a certain processing task, and the effectiveness of the method was verified by a case study.