A building method and a building system for panorama point cloud data are provided. The building method for panorama point cloud data includes the following steps. At least one reference geometric object located at an overlap region of two adjacent three-dimensional capturing devices is captured by the two adjacent three-dimensional capturing devices to obtain two reference point cloud sets. A reference feature plane is obtained from each of the reference point cloud sets. A coordinate transformation matrix is obtained according to the reference feature planes. A plurality of real-time point cloud sets are obtained by the three-dimensional capturing devices. The coordinate transformation of the real-time point cloud sets are performed according to the coordinate transformation matrix, and the real-time point cloud sets are combined to obtain the panorama point cloud data.