The invention discloses a maintenance path planning method and device for a nuclear power plant. The method includes: according to the distribution of radiation zones and radiation hotspots in the nuclear power plant, making a three-dimensional digital nuclear power plant into a navigation grid required for path finding; according to a preset heuristic search algorithm, selecting a suitable maintenance path in the navigation grid , so that the maintenance personnel who pass the maintenance path receive the lowest radiation dose. In the present invention, by introducing radiation data information into the three-dimensional scene of the nuclear power plant, the dose level of maintenance exposure is used as the evaluation standard for path search, and the heuristic search method is used to automatically search for the path in the three-dimensional scene of the nuclear power plant. Under reasonable and as low as possible level conditions, it can effectively approach the maintenance target area, providing maintenance personnel with excellent maintenance path planning, and at the same time, it also greatly improves the efficiency of maintenance path planning, so that the maintenance of nuclear power plants can be carried out quickly and reliably.