A new technology named multi-thermal fluids, as an innovative technology for offshore heavy oil, has been used in pilot test of Bohai oilfield, but the mechanism of multi-thermal fluids on enhanced oil recovery and reservoir adaptability has still not enough indepth research. Through theoretical analysis, numerical simulation and experiment analysis, the stimulation mechanism of components in multi-thermal fluids and the coupling of components was studied to discuss the mechanism of multi-thermal fluids on enhanced oil recovery; at the same time, based on crude oil viscosity, permeability, heterogeneity parameters and other data from heavy oil reservoirs in Bohai oilfield, the effect of multi-thermal fluids and the adapted reservoir conditions were compared with steam stimulation. The results show that: compared with steam stimulation, the multi-thermal fluid can enlarge heating volume, increase formation energy, reduce heat loss, and so on, but it carries less total enthalpy. As a result, multi-thermal fluids technology is more suitable for the heavy oil reservoirs which have relatively low oil viscosity, weak heterogeneity, thin oil layer and small natural energy.