Currently, the world’s technological powers are actively exploring key issues such as mechanisms, paths, and policies for promoting innovation through Open Science. What is the relationship between the front end “Open Science” and the back end “Product development” for innovation process? At present, academic circles pay little attention to it. In reality, the Open Science behavior of pharmaceutical enterprises is extremely active, so will Open Science have an impact on Product development? This is an interesting question. Based on the sample of listed pharmaceutical companies in China, we reveal the internal mechanism of Open Science on Product development. This study finds that Open Science strategy has a significant positive impact on Product development, which is specifically shown as: (1) The higher the frequency of Open Science, the more positive the impact on Product development; (2) The higher the level of Open Science, the more positive the impact on Product development; (3) The lag time of the impact is usually three years, which means the best impact effect is within 3 years. We provide theoretical basis, management and policy implications for the choice of Open Science strategy, the improvement of basic research capabilities, and the effectiveness of national innovation systems. We expand the theory of open innovation.