Abstract: Longyou ancient underground cavern No.23 is measured nondestructive using equipment such as GPS,total station, automatic compensated level. According to the characteristics of the ancient cavern, closed traverse control survey method is used for the plane control survey, closing level line survey method is used for elevation control measurement. Plane dimension size of this cave, elevation size of hole and rock pillars, section size of cave body are detailed surveyed and mapped.3D model of the ancient cavern is build through software such as AUTOCAD Cyclone ANSYS,which provides new ideas for follow-up numerical simulation, for nondestructive protection and repair work.