Abstract: Based on the variation cycle of tidal force, the continuous daily variation characteristics of Out Long-wave Radiation (OLR) from June 30 to August 30 in a large area (17°～55°N, 73°～136°E) of the Chinese mainland were analyzed by using the FY-3E satellite OLR data, and the correlation characteristics of tidal force, OLR and the Ms5.5 earthquake in Pingyuan County, Dezhou on August 6, 2023 is discussed. The images of OLR changes monitored synchronously according to the cycle of tidal force changes show that: (1) during the cycle of tidal force changes (A and B cycle before the earthquake and D cycle after the earthquake), OLR near the epicenter shows no significant changes; while the continuous OLR anomalies are observed synchronously during the C cycle of seismogenesis, and accompanied by the continuous change of tidal force from trough to peak to trough, the OLR anomalies show the stage characteristics of initial warming-strengthening-peak-attenuation-gradually calming, which are synchronous in time. (2) OLR anomalies are closely distributed around the Liaocheng-Lankou fault in space, indicating that seismic tectonic movement is the main cause of OLR anomalies of the earthquake, and the evolution characteristics of OLR anomalies during the earthquake is the radiation representation of seismic tectonic stress changes. (3) The earthquake occurred near the peak phase point of the C cycle, combining with the synchronous monitoring of the enhanced characteristics of the OLR anomalies, it is shown that when the seismic tectonic stress accumulates to the critical state of rock fracture and sliding, the sudden change of the size and direction of the tidal force promotes the instability of the Liaocheng-Lankou fault and induces the earthquake. The above results also show that the OLR products of FY-3E satellite can be well applied to the research of seismic infrared anomalies.