High-entropy alloys overcome the design limitations of traditional alloys because of their multiple principal element characteristics and excellent mechanical properties. Recent studies have shown that chemical ordering is common in high-entropy alloys. In this paper, the formation mechanism, regulation methods, characterization techniques and their effects on the mechanical properties of chemical short-range order materials are reviewed. The formation of chemical order in the alloy is affected by many factors, such as the mixing enthalpy and atomic size. The degree of chemical order in an alloy can be controlled by heat treatment, interstitial atom doping and irradiation treatment. X-ray diffraction, transmission electron microscopy and computer simulation are common methods used to characterize chemical order. The chemical order of an alloy affects its mechanical properties by affecting its dislocation behavior and stacking fault energy. An in-depth understanding of chemical order provides an important basis for improving the performance of high-entropy alloys through composition design and processing technology.