A series of sensitivity experiments on the Late Ordovician Earth’s climate under different orbital configurations were conducted using the atmosphere-ocean general circulation model CESM1.2.2. It was found that the local annual mean surface temperature could vary by more than 5.5℃ and the seasonal temperature by more than 23℃ due to changes in orbital parameters. The global mean temperature was affected by less than 0.2℃ due to precession, and an increase of about 1℃ in the global mean temperature could be caused by a change in obliquity from 22.5° to 24.5°, due to the annual mean solar radiation received at high latitudes, together with the ice-albedo feedback. The global mean precipitation rate was found not to be impacted by orbital changes, but its spatial and temporal distribution was highly impacted; the north-south shift of the intertropical convergence zone was controlled by the precession, and an increase in precipitation at the poles was caused by increases in the obliquity. A great impact on the spatial pattern of summer monsoonal regions was also caused by orbital changes. A change in the global monsoon area by more than 40% could be caused by changes in precession; a mild effect on the mid-latitude and high-latitude monsoon area of approximately 10% was caused by obliquity. Although Late Ordovician was overall warm with its global mean surface temperature exceeding 18℃, deep snow can be accumulated over large areas of continents in the southern hemisphere under most orbital configurations, indicating the possibility of the formation of large ice sheets.