High-entropy alloys, which usually composed of 4 or more elements in equiatomic or near equiatomic ratio with a solid solution structures, have emerged as a new kind of metallic materials for a recent decade. The proposed philosophy of high-entropy alloys has broken through the paradigm of traditional alloy design and largely expanded the scope of alloy exploration. Meanwhile, high-entropy alloys exhibit several unique properties, such as high strength and hardness, unusual low-temperature toughness, high corrosion resistance and radiation resistance, due to the large lattice distortion, high mixing entropy, slow diffusion of atoms and cocktail effects. In this paper, we made a brief summary of the present research on high-entropy alloys, and discussed the potential applications of high-entropy alloys in extreme environments as new-emerged structural materials. In particular, the possibility of high-entropy alloys used in the key components of petroleum industries, e.g. drill pipe joint belt, bushing and high-performance riser, etc., was emphatically analyzed.