A theoretical and empirical study on the fuzzy front end innovation in new product development: Abstract: Using some large and medium-sized enterprises of Chinese manufacturing industries as the investigation target, a large-scale research on the key factors with regard to Fuzzy Front End (FFE) innovation of New Product Development (NPD) is conducted. An analytical framework, research hypotheses, and a causal model between FFE key factors and NPD project performance is constructed by literature review. The causal model is tested with AMOS using the data from 160 completed NPD projects in manufacturing enterprises. The results are summarized as follows: first, the reduction of technical and market uncertainties during the FFE have different level of positive impact on the efficiency and effectiveness of NPD projects. Second, the intensity of initial plan has different level of positive impact on the reduction of technical and market uncertainties. Finally, for the industry goods firms, it is relatively easy for managers to develop the initial plan, and it has a greater impact on the reduction of market uncertainty compared with the consumer goods firms.