To investigate the anomalies and formation mechanisms of outgoing longwave radiation (OLR) during earthquake preparation, this study employs wavelet transform and power spectrum estimation to analyze the OLR information related to the 2025 M6.8 Dingri earthquake on the basis of the OLR data from the Fengyun geostationary satellites and reanalysis datasets from the European Centre for Medium-Range Weather Forecasts. The results indicate that (1) approximately 90 days before the earthquake (around October 9, 2024), a significant OLR power spectrum anomaly began to appear near the epicentral area. This anomaly peaked on October 12, 2024, with its intensity persistently deviating from the multiyear average and exceeding two standard deviations for 32 and 9 days, respectively. The anomalous area was primarily concentrated in three zones centered at the epicenter, with the most prominent zone located over the Tangra Yumco—Dingri and Yarlung Zangbo River fault zones northwest of the epicenter, exhibiting an anomaly amplitude as high as 10.4 times the normal level. (2) At the peak of the OLR power spectrum, meteorological conditions near the epicenter were characterized by low surface air temperature, high total cloud cover and surface latent heat flux, and low total precipitation, coupled with a significant deficit in atmospheric water vapor content. These conditions are inconducive to OLR enhancement, preliminarily suggesting that the anomalies were not directly related to atmospheric environmental conditions but more likely attributable to the accumulation of regional tectonic stress and the intense activity of active structures before the earthquake. The spatiotemporal characteristics of OLR power spectrum anomalies before the Dingri M6.8 earthquake are largely consistent with previous findings, offering a reference for determining the timing and location of strong earthquake predictions.