Abstract: As inevitable byproduct,tar of combustible gas,obtained from the pyrolytic gasificationprocess of straw biomass,had many characteristics.The formingreaction process of tar was extremely complex,there were many factors affecting its content,included straw resource type and its characteristics,gasification equipment types and its internal structure,and gasification process conditions（gasification medium,air input,catalyst,gasification temperature and gas retention time）.Several abovefactors were reviewed and some reference think ing was put forward for solving the tar problems,in order to promote the application of biomass gasification technology in the vast rural areas.