Abstract: Considering the unbalanced team chamber and low productive degree in extra-heavy oil filed development by steam assisted gravity drainage(SAGD),the technology of composite huff and puff improving SAGD performance was studied.The feasibility of composite huff and puff was demonstrated by high temperature and high pressure physical simulation experiment and the numerical simulation of SAGD.The mechanism of compound steam huff and puff of high temperature dispersant,nitrogen and steam was expounded.The results indicate the high temperature dispersant has a miscible effect and dispersion effect,which can improve the SAGD connectivity between wells of the thermal recovery.High temperature dispersant+nitrogen+steam stimulation can effectively improve the SAGD steam chamber development degree,improve the development effect of SAGD.The amount of nitrogen injection should be matched with the volume of the steam chamber,and the nitrogen should be injected into the steam injection well before the steam injection.This technology was implemented in 19 wells,and the average incensement oil production of single well is 4.6 t/d,the practice shows that the technology meets the requirements to further improve the development effect of SAGD.