Abstract: The construction of emulsion system with high physical stability is pivotal to effectively increase the bioavailability of krill oil and broaden its application in health food. This study aimed to investigate the effects and potential mechanism of the interaction between endogenous phospholipids and whey protein isolate(WPI) on the physicochemical properties, microstructure and physical stability of krill oil emulsion. The results showed that when the oil load increased to 25%, the average particle size and zeta potential value of krill oil emulsion reached 35.03 nm and −27.3 mV, respectively, emulsion tended to be more unstable. The addition of WPI 0.5% (w/v) increased the average particle size and Zeta potential value of krill oil emulsion by 84.0% and 31.40%(P<0.05), respectively. Meanwhile, the apparent viscosity values at low shear rate of krill oil emulsion increased by 7-folds(P<0.05), and the turbiscan stability index(TSI) value decreased by 70.3%(P<0.05), thereby leading to stable emulsion. Further results showed that endogenous phospholipids could interact with WPI to improve its interfacial activity, reduce α-helix content in WPI by 1.60%(P<0.05) and evidently enhance its endogenous fluorescence intensity and surface hydrophobicity. The environmental stress stability demonstrated that the simulated pasteurization heat treatment improved the physical stability of krill oil emulsion. In addition, the krill oil emulsion exhibited relatively strong stability when the pH values migrated toward weak alkaline(pH6~9). Therefore, the interaction of endogenous phospholipids and WPI would provide the possibility to construct krill oil emulsion with high physical stability and broadened its application in health food.