Abstract: The environmental characteristics of asteroids not only are fundamental issues in related scientific researches, but also constitute a principal factor that needs to be comprehensively considered in designing the corresponding exploration missions. This paper reviews the studies of the environmental characteristics of a couple of accessible asteroids in three aspects: the peripheral space environment, the surficial environment, and the internal environment. This paper also discusses the characteristics of two target objects of China’s first asteroid exploration mission announced by China National Space Administration, namely, the near-Earth asteroid (469219) 2016HO₃ and the main-belt comet 133P/Elst-Pizarro, focusing on their physical and environmental features.