As an important component of modern industrial system, power system is re-lated to the lifeline of national economy and national energy security. With the increase of the number of the user input, its communication security has attracted more and more attention. Quantum key distribution (QKD) enables secure remote information transmission between two users theoretically. Therefore, the combination of QKD and the existing power communication network can better ensure the security of the existing power service transmis-sion. However, since optical signals and quantum signals need to share a set of optical fiber transmission equipment, there will be resource competition between the two parts, and it is necessary to strike a balance between power service reliability and secure key rate (SKR). Therefore, a dynamic power regulation (DPR) scheme is designed in this paper. Based on the \(\varepsilon\) -greedy algorithm, the transmitted power can be dynamically adjusted according to the condition of quantum key pool (QKP), so as to jointly optimize the relia-bility of power service and SKR. The results show that DPR scheme can ef-fectively reduce the probability of key resource depletion or overflow in QKP while ensuring the reliability of power service.