Offshore gas hydrates is hosting in the environmental condition of low temperature and high pressure. Drilling in hydrate formation with decomposing inhibition technology, drilling fluid temperature is often lowered to inhibit hydrate dissociation, so low temperature performance of drilling fluid is important. Study was made on the rheology property of formate seawater drilling fluid and polymeric alcohol seawater drilling fluid at different low temperatures; the result showed there was certain degree influence on low temperature rheology property of drilling fluid by both drilling fluid additive and hydrate inhibitor. Reasonable selection on drilling fluid system and additive should be taken into account in the study on drilling fluid for offshore gas hydrate drilling to ensure its good rheology at low temperature.