The spatio-temporal distribution of delay time of S-wave splitting is analyzed based on 260 shear wave time-delay data from local earthquakes in Tengchong area, Yunnan Province. The result shows that the changes in delay time of S-wave splitting are related to the magnitude of three moderate and small earthquake swarms, and delay time of S-wave splitting changes synchronously with the occurrence of the main shock and larger aftershocks in the earthquake swarm which carries the information of stress change during the earthquake swarm, provided that the locations of all earthquakes in the same earthquake swarm are concentrated, thus excluding the influence of differences in propagation path length and spatial azimuth of seismic ray path on delay time of S-wave splitting. Different from most cases in the past, the magnitude of the earthquake swarm in this work is relatively small, with the maximum magnitude ranging from M3.2 to M5.2. At the same time, the distances between the earthquake swarms and the stations are relatively large, generally greater than 30 km, and the largest reaches about 70 km. The information of stress changes during moderate and small earthquakes has been obtained by analyzing delay time of S-wave splitting from distant stations, which has great implications for the wider use of distant small earthquakes to monitor regional stress changes.