Gum arabic (GA) is the most widely used natural emulsifier in food industry. However, due to its high price and unstable market supply, the search for substitutes of gum arabic has attracted the attention of researchers. Recent studies have shown that sugar beet pectin (SBP) has great potential as a natural emulsifier. However, the mechanisms and differences of GA- and SBP-stabilized emulsions are still unclear. In this study, the interfacial behavior of GA and SBP on the oil-water interface was studied and compared through dissipative quartz crystal microbalance and interfacial dilatational rheology. Then, droplet size, zeta-potential and viscosity of the emulsion stabilized by GA and SBP were measured. Meanwhile, the long-term stability of GA- and SBP-stabilized emulsions was evaluated and compared through a LUMiSizer stability analyzer. The study showed that at the same concentration, SBP-stabilized emulsion had significant advantages of a smaller droplet size, a larger viscosity, a thicker and more elastic interfacial layer, and better long-term stability. A comparison of the long-term stability of SBP2.0%- and GA15.0%-stabilized emulsions, evidenced that the elasticity of the interfacial layer plays a crucial role in the long-term stability of emulsions. This research may provide useful information for finding alternatives to GA.