Abstract: Abstract: Under the background of transformation, the late-comers are faced with both technology and market disadvantages. How to use external knowledge and resources to achieve the catch-up goal of technology and market has attracted much attention. This study integrates the theories of innovation search, catching-up and organizational legitimacy, constructs the impact model of parallel search on synergistic catching-up of late-comers, and conducts empirical analysis with 212 samples. The results show that both leading search and following search have inverted U-shaped effect on synergistic catching-up (SCU). External legitimacy has a positively moderating effect on the relationship between leading search and SCU, but negatively moderates the relationship between following search and SCU. The moderating effects of internal legitimacy are also opposite. Furthermore, the integration of internal and external legitimacy has a positive effect on parallel search and SCU. This study not only enriches the relationship between parallel search and SCU, but has practical significance for Chinese late-comers to achieve innovation leap.