In order to study the diseases and preservation state of the Qianlong imperial monument located in the Beijing Capital Museum, we evaluated the degree of its weathering, the development of surface fissures, and its surface contamination and discoloration using a variety of nondestructive and small-sample invasive techniques such as digital photography, nonmetal ultrasonic detection, tape bonding force testing, as well as the use of a portable chromometer and a portable video microscope. The results show that surface pollution and discoloration are the main diseases of the Qianlong imperial monument. Slight crusting, scaling, erosion and fissure development also exist on some parts of the monument, but overall the degree of weathering is not severe.So far, the Qianlong imperial monument is in a fairly good state of preservation. This study could provide a reference for subsequent protection measures.