Abstract: Objective: To explore new graduate nurses' changes of occupational stress and to identify factors that impact on their transition to the workforce. Methods: This study applied a longitudinal design with four follow-ups survey during 2014 and 2015. Results: The mean score of occupational stress was 2.63±0.10, and reached highest in the fourth month (2.75±0.68). The four domains and total score varied significantly during the first year (P<0.05). Tasks in critical care was the strongest stressor and reached highest in the fourth month after employment (3.29±0.85); tasks in general care got highest in the very beginning (2.90±0.84); leadership and management reached highest in the fourth month (2.68±0.85) and interpersonal relationships got highest score in the eighth month (2.41±0.81). Occupational stress was significantly correlated with residence, education background, rotation and work independently in day shift (P<0.05). Conclusion: Occupational stress of new graduate nurses changed with time in the first year of employment. Nursing managers need to identify impact factors of different stages, provide appropriate orientation for new graduate nurses to adapt to their work environment.