The invention discloses a method for calculating a navigation path in a three-dimensional environment. The method comprises the steps that indoor navigation path calculation and outdoor navigation path calculation are combined, three types of paths are calculated at the same time, the shortest path between the outlet serial number of a building where a starting point is located and the inlet serial number of a building where an end point is located, the shortest path between the outlet serial number of the building where the starting point is located and the inlet serial number of the building where the end point is located and the shortest path between the inlet serial number of the building where the end point is located and the end point serial number are calculated respectively, the calculation results of the three paths are fused, and therefore an optimal comprehensive path calculation result is obtained. According to the path design method by fusing the indoor and outdoor navigation paths, indoor navigation path calculation and outdoor navigation path calculation are fused, the information of the three paths is calculated at the same time, and therefore indoor and outdoor integrated navigation path calculation is rapidly achieved in the three-dimensional space.