The Mizhi ancient town is located in northern Loess plateau, a dry and cold area. These cave dwellings were built during the period of the Qing dynasty till the Republic of China, which are well preserved and still used as residential area. Now, with the change of social system and the devel- opment of economy, one house built for one family has become a place where many families living together. In this paper, we try to figure out the current use and the renovation process of these houses.

 Through the data collection, interviews, measurement and case analysis, the following conclusions can be drawn.

 1. In 1948, because of the Land Revolution, the homes of the some richer families were allocated to the landless and homeless citizens, and gradually the pattern of multiple families living together. In the past, each building of Siheyuan had corresponding functions, but now a family is composed of one room. After 2000, due to the development of the new town, many aborigines of the old town moved to the new place, while on the other hand, the low rent of the old town attracted a large number of families from the countryside. According to the surveys from the residents, we found out that three-quarters of the people living there are tenants while the rest are owners. Most tenants choose to live in this ancient city not only because of the decline of the rural schools but also their desiring for better education on their children.

 2. A unit consists of several rooms and one courtyard, where people’s private activities are usually carried out in their own rooms, such as cooking, studying, sleeping, resting, eating and so on. A common water supply is set in the courtyard, hence the laundry and drying are usually done in the courtyard. Usually, toilet sets up in the corner and generally, the courtyard and toilet are cleaned by each family. Courtyards can be divided into 5 categories according to the way they have been used. They are 1. only owner living, 2. one owner living with other renters, 3. multiple owners living with multiple renters, 4. only renters living, 5. mixed type. They also assisted each other in the yard by cleaning and maintenance.

 3. The expansion and renovation of the residences were mainly done by the owner households between 1990 and 2008, in order to improve the living environment such as kitchens and flush toilets and obtain rent. In addition, a small number of cases were seen in which the house was divided into several parts including the courtyard.

 4. Because the space of Yao-dong can not be subdivided, it is used as the minimum unit of living space. In the cold region such as Mizhi city, Yaodong with thick walls of earth and stone has good heat preservation and because the space is highly independent, it is suited to use as one room. The stable structure and independent space units of Yao-dong are suitable for nuclear families in the modern society.