This paper briefly introduces the current research progress in the field of the stress drop both in China and abroad. We briefly describe the definition and calculation method for the stress drop,the overall characteristics of stress drop and the correlation between stress drop and magnitude,tectonic system and other factors. The article focuses on the possible applications of the stress drop in the post-seismic trend determination,and discusses in detail the uncertainty of the stress drop calculation result. Stress drop represents the stress change on the dislocation surface of an earthquake with instantaneous dislocation,which is defined as the difference between the initial stress σ₀ before earthquake and the termination stress σ₁ of post-earthquake. The stress drop value released by the earthquake is generally between a few MPa to dozens of MPa,most being below 10MPa. The relationship between stress drop and magnitude,source depth,tectonic system,source mechanism and sequence type is complex and different. The stress drop of earthquake sequence increases continuously with time after eliminating the influence of magnitude,which has certain time indication significance for subsequent strong aftershocks. However,it is worth noting that many factors affect the calculation of stress drop. The numerical experiment results show that the combined error of the corner frequency and zero frequency limits has a significant influence on the stress drop calculation result. The error bar almost completely covers variety of the stress drop of the aftershock over time.