In this paper,by introducing a gesture recognition technology into the human computer interaction in virtual assembly,a hierarchical interaction hand gesture model is proposed to improve the user experience in virtual assembly tasks.According to the characteristics of assembly tasks and interactive modes,a two-level gesture recognition strategy is designed.In the strategy,firstly,interaction hand gestures are preliminarily classified,and the types of the hand gestures are identified on the basis of context-awareness.Next,a gesture semantic is recognized by capturing the motion features of hand.Then,different interaction modes are integrated seamlessly by estimating the functional region of hand workspace,and thus,users' difficulty in recognition is reduced.Experiment results show that the proposed model and recognition method can effectively improve both the human computer interaction efficiency and the user experience in a virtual assembly prototype system.