As an important factor of innovation, knowledge plays a vital role in promoting the growth of innovation ability. In recent years, many scholars have explored the influence of knowledge network structure on innovation. The hydrogen energy industry is highly technical and covers a wide range, which is in urgent need of regional cooperation and easy to form a knowledge network. The function of the knowledge network depends on inter-organizational communication, so traffic development may be a boundary condition. This paper takes the hydrogen energy industry as an example to study the influence mechanism of the knowledge network on regional innovation ability and explore the moderate effect of high-speed rail opening. This paper takes hydrogen patents as samples, uses backward citation data to construct the knowledge network, and conducts regression tests. The results show that the density of the knowledge network has a negative effect on regional innovation ability, while the structural hole and centrality have a positive effect. The opening of high-speed rail will strengthen the influence of density and structural holes, and weaken the influence of centrality. Finally, it is proposed that the development of the hydrogen energy industry should reduce the dependence on the network, and the government should prevent the loss of large enterprises.