Using the method of multi case grounded theory, this paper summarizes the influencing factors of radical technological innovation in equipment manufacturing industry under three reverse R D outsourcing modes: R D cooperation, establishment of overseas R D center and overseas M A, and constructs the mechanism model of radical technological innovation in equipment manufacturing industry. On this basis, through the fuzzy set qualitative comparative analysis of the data of 27 typical case enterprises, the multiple causal paths for enterprises to realize radical technological innovation under different reverse R D outsourcing modes are obtained. The research shows that reverse R D outsourcing through R D cooperation cannot help enterprises achieve radical technological innovation in the short term, while enterprises that carry out reverse R D outsourcing through the establishment of overseas R D centers and overseas M A can achieve radical technological innovation through four paths. Through the establishment of overseas R D centers to carry out reverse R D outsourcing, exploitative learning is the core condition for the occurrence of radical technological innovation. The reverse R D outsourcing through overseas M A and exploratory learning are the core conditions for the emergence of radical technological innovation. Through further analysis, it is found that there are three antecedent factor configurations, which makes the reverse R D outsourcing based on overseas M A fail to achieve the expected radical technological innovation.