The purposes of this study are to understand the state of fatigue of clinical nurses and its correlation factors. A modified questionnaire that includes subjective symptoms of fatigue was used as the investigation method. A total of 432 subjects were completed in this study which include 356 clinical nurses (observed group) and 76 college staff (contrast group). The result shows that the top 5 prevalence in observed group was visual fatigue, drowsiness, yawning, want to lie down and waist pain. The fatigue level of observed group was more serious than contrast group. Fatigue values of nurses were significantly related to hospital type, division. position, marriage state, children numbers, work hours and shift work. The top 5 self-conscious effecting factors of fatigue of nurses were work loading, shift work, salary, health and stress.