Since interior cracks are the most important factor imperiling stone sculptures, it is necessary to understand the development of cracks inside such objects to make a conservation plan of action. Ultrasonic CT is a newly developed technique for assessing the weathering condition of stone. This article discusses the application of the ultrasonic CT scanning technique on weathering to assess the condition of stone sculptures at the Qianling Mausoleum. Limestone test sample blocks was prepared in the lab. Two round blocks with diameters of 50cm and two rectangular samples with side lengths of 50cm were made with 5cm diameter round holes and 5cm x 15cm square holes, respectively. A ZBL-U520 digital CT scan was used to identify the holes. The CT scanner was used to test the interior cracks of Qianling Mausoleum sculptures and the results were compared with endoscopy results. The results by CT scan is proved to be accurate.