Subacute rumen acidosis is a common nutritional metabolic disease in ruminant production.Its onset is slow and the clinical manifestations are not obvious,which makes the digestive system of ruminants dysfunctional,accompanied by ruminitis,laminitis,mastitis,liver abscess and other complications,seriously affecting the economic benefits of the breeding industry.A large number of studies have found that a thiamine supplementation to ruminant diets can effectively relieve subacute rumen acidosis and increase rumen pH to maintain the stability of rumen environment.This article discusses the pathogenesis of subacute rumen acidosis,the relationship between thiamine and subacute rumen acidosis,and the action pathway of thiamine in relieving subacute ruminal acidosis,to provide a theoretical reference for the application of thiamine in ruminant production.