<p>This study proposes a group key service node placement method for quantum key distribution (QKD) networks based on partially trusted relays, aiming to optimize network structure, improve key distribution efficiency, reduce communication delay, and ensure transmission integrity and confidentiality. Based on graph theory, a key information model for the quantum key distribution network is established, which defines node types, functions, and connectivity. Leveraging the secure transmission protocol of quantum keys, the unconditional security of the key during transmission is ensured. Furthermore, this study proposes a QKD network architecture incorporating partially trusted relays, which combines trusted and untrusted relay technologies. An improved p-median model is introduced and solved using a greedy algorithm to ensure secure quantum key distribution and optimal deployment of group key service nodes. Experimental results demonstrate that the location of group key service nodes in quantum key distribution network ensures the minimum number of key service nodes and minimizes the path length from network demand nodes to group key service nodes. Furthermore, this method significantly improves the key distribution efficiency, success rate, security, energy consumption, resource consumption, network coverage, and blind area of quantum key distribution network.</p>