Luopan, it’s a tool used for investigating the geomantic omen, consists mainly of a celestial pool in the center of the disk and a series of concentric circles. Tianchi is composed of thimble, magnetic needle, submarine line, outer box and glass cover, fixed in the center of the inner disk. The seabed is the bottom of the Tianchi lake，there is a red line on it, named “submarine line”. The outer plate is inlaid with wood into a circle with several concentric circles. And the disk surface is painted with black lacquer, each concentric circle is painted with eight diagrams, stars and other patterns, and has 24 solar terms and other words.