<p>Knowledge resources are a critical element of firms’ core competitiveness. Many firms have suffered significant losses due to their failure to address the issue of knowledge loss, which has become a major challenge affecting their survival and development. To prevent and manage technical knowledge loss in firms, this study proposes an invulnerability analysis model for the firms’ technical knowledge network (FTKN) is first proposed based on complex networks. Key invulnerability metrics such as network connectivity, average risk path, and network risk efficiency are defined according to the unique characteristics of FTKN. Besides, the invulnerability of FTKN is analyzed based on the simulation analysis of random attacks and deliberate attacks. Additionally, a node importance evaluation method is introduced, incorporating factors such as degree value, betweenness centrality, efficiency, and the contributions of adjacent nodes. To enhance the survivability of FTKN, the network structure is optimized through redundant design. Simulation results demonstrate that external deliberate attacks and technical blockades cause more damage to the system compared to attacks on strongly correlated technologies. From a short-term perspective, prioritizing the protection of nodes with high betweenness can greatly improve the invulnerability of the network. Conversely, from a long-term perspective, the protection strategy of firms for moderate technology nodes is more conducive to the connectivity of the entire technology evolution network. Firms should adopt strategies such as redundancy backup of key technologies/equipment, classified protection of technical talents, and establishment of technical knowledge security early warning control mechanisms to enhance the survivability of firms’ technical systems.</p>