The subject of Ecology is the theoretic basis of ecological civilization construction. There is a significant feature of special subjects of ecology advancement, with the development of modern ecology and its combination with regionally characteristic ecology. It has become the significant basis of regional ecological civilization construction, particularly in arid and semiarid regions. In regard to desert ecology, the study areas include desert and desertified lands, and the research subject is desert biology. In this context, desert ecology is a crossing and integrated subject of desert and ecology subject systems, and indicates a typically regional feature. We focus on the definition and subject orientation of desert ecology, and analyze its subject characteristics and discipline advantage. There is a proposed concept of Desert Ecology that can be defined as the interactive relationship between desert biology and desert environments. It includes the effect of desert environments on desert biology (i.e., desert biology and cryptozonal organism), and the response and adaptation of desert biology to the alteration of desert environments. On the context of study area and subjects of biology, the special Desert Ecology refers to desert environments and the desert biology dwelling in it. There is in fact a general desert environment including not only desert ecosystems but also the arid and semiarid desertified areas, which give birth to the general concept of Desert Ecology. This general concept of Desert Ecology focuses more on the anthropogenic impact on the relationship between human activities and desert environments, and the new questions induced within them. Based on research content and range of desert ecology subject system, there are inherent science topics needed within desert ecology subject that characterize the exclusivity from other ecology subjects, i.e., grassland ecology, forest ecology, and agriculture ecology. The rich research content and theoretical perfection of desert ecology can be in favor of the systematic research on the reason, process and principals of desertification, and uncovering the restoration mechanism of reversal process of desertification. All these are helpful for measures of desertification control, and the utilization of desert resources and protection of desert ecosystems in semiarid and arid regions. In sum, the special subjects of ecology acted as Desert Ecology can provide theoretical basis for regional desertification control and state ecological construction of "Three-north Forest Protection Project".