On November 17，2021， an MS5.3 earthquake occurred in the offshore area of Yancheng， Jiangsu Province， China. The seismogenic mechanism and its causes have attracted extensive attention of earth scientists. To analyze the causes of the earthquake， it is necessary to accurately determine the focal mechanism solution of the earthquake and the regional stress field. In this study， a credible central focal mechanism solution was determined by synthesizing the focal mechanisms of various institutions. To ensure the accuracy of solving the stress field in the source region， this study collects the historical source mechanism solution data around the earthquake before 2016， and uses the earthquake observation report to obtain 22 source mechanism solutions after 2016. The combined source mechanism solution data is used to solve the stress field around the MS5.3 earthquake in Yancheng Sea， Jiangsu Province. The final results are as follows： the central focal mechanism of MS5.3 earthquake in Yancheng Sea area of Jiangsu Province plane I strike angle is 104.95°， dip angle is 70.91°， slip angle is 26.45°， plane II strike angle is 5.70°， dip angle is 65.11°， slip angle is 158.86°； The predominant direction of main compressive stress in this area is ENE-WSW， and the dominant direction of stress is NWN-SES. Projecting the stress field onto the central focal mechanism's planes， both of planes are at a high level of relative shear stress， indicating that the earthquake occurred at the maximum shear stress release plane under the action of the tectonic stress field. It is a normal release after stress accumulation， and the possibility of a large earthquake occurring around is reduced. Considering that the relative shear stress projected by the stress field to Ilane II is larger than that of Plane I， and Plane II is closer to the strike of the Subei-Binhai fault， it is determined that the plane II is the seismogenic fault plane of this earthquake.
