For the M_S6.0 earthquake in Laos on November 21,2019,tidal variations were calculated before and after the earthquake(from October 16 to December 15,2019)at the epicenter(19.50°N,101.35°E). The gravitational tidal force was near its high-phase point at the time of the earthquake,indicating that the induced seismic effect belonged to the typical type of positive fault strike-slip action. The distribution of long wave radiation anomalies and changes in the NOAA Outgoing Long Wave Radiation(OLR)data were calculated for each tidal cycle in the study area(13°N～23°N,99°E～109°E)against the background of the low-phase points of the tidal cycle(October 28,November 13,and November 27). The results show no OLR change near the epicenter during the A and B cycles of no-seismic tidal variation. However,during the C cycle of the tidal change associated with the earthquake,a significant and continuous OLR anomaly was observed only at the epicenter. Spatially,the OLR anomalies are distributed along the Dien Bien Phu fault zone in northeastern-southwestern trending northern Laos,coinciding with the epicenter location. Temporally,the anomalies followed a process of warming,anomalous enhancement,peak,attenuation,seismicity,and calm. This pattern aligns with the mechanical process of rock stress-loaded rupture evolution:initial micro-motion rupture,dilatational rupture,stress locking,seismicity,and calm. These observations indicate that the tidal force of celestial bodies can induce activity in faults that are in a critical state. Furthermore,OLR anomalies represent the stress-strain processes within the earthquake structure.