Abstract: Objective To assess the human engineering risk in a mask production factory and then to improve the workers' working condition. Methods RULA (rapid upper limb assessment) was used to identify the ergonomics risks in a mask production factory,and to evaluate task severity and rank risk level for workers' wrist,arm,neck,torso and leg during the operation. Results Human engineering risks in two workplaces, namely the separation and lifting of filter jumbo were both ranked 7 points, which indicated both workplaces had high risks. After that, the improvement actions, including manual task replacement,the process optimization, were taken accordingly to reduce risk level. Conclusion RULA is an effective tool in assessing human engineering risks in a mask production factory, which indicated this tool can be used in more fields.