Abstract: The storage stability and mechanism of hydrogen donor thermal cracking (HDTC) of oil-sand bitumen was studied under different reaction conditions by investigating the changes in density，kinematic viscosity，stability，asphaltene content and toluene insoluble material content with the prolonging storage time and comparing with the results of visbreaking. The results show that the density，kinematic viscosity, content of asphaltene and toluene insoluble material increase greatly after visbreaking and hydrogen donor thermal cracking as the storage time increases, indicating the stability deterioration of the upgraded oils. Compared to the thermal visbreaking results, the increasing range of above parameters using HDTC is smaller. The spot test level of HDTC upgraded oil is not greater than No.2，which meets the stability requirements of transportation, demonstrating that the storage stability is superior to the conventional visbreaking upgrading oil after long-time storage. The main reasons for stability improvement are hydrogen donor effect and improved stability of resin system.

Key words: hydrogen donor thermal cracking, upgraded oil, storage stability, viscosity, stability