Based on the tide period indicating background time,the synchronous changes of outgoing long-wave radiation(OLR)and remote sensing atmospheric temperature(AT)during the Tangshan M5.1 earthquake in Hebei Province are analyzed. The results showed that the earthquake occurred at the time when the tidal force was relatively high and from July 5,2020 to July 13,2020,with the continuous increase of tidal force from the trough to the peak,the OLR and the AT experienced the synchronous changes of quiet-enhancement-peak before the earthquake and rapid attenuation after the earthquake. Our results suggested that the tidal force has changed the accumulation unbalance process of in-situ stress in the structure and has the effect of triggering earthquake. The quasi synchronous changes of OLR and AT indirectly reflected the change process of in-situ stress of the earthquake.