Innovation resource is important factor that affects the development of enterprise innovation. Embedded network is important channel to acquire innovation resource. In the context of institution constraints, the success of radical innovation depends largely on the legitimacy support. Based on the literature review, we developed an analytic framework on the relationship between network embeddedness, innovation legitimacy and resource acquisition. In this paper, we chose three representatives and employed a multiple-case study method, and the conclusions include: the structural, relational and cognitive network embeddedness have positive impact on innovation resource acquisition and innovation legitimacy; the pragmatic, moral, cognitive innovation legitimacy have positive impact on innovation resource acquisition, and the network embeddedness has positive impact on innovation resource acquisition by the mediating effect of innovation legitimacy. The research conclusion has important implication for Chinese enterprises in institutional transition to carry out innovation as well as building legitimacy successfully.