Emulsified asphalt is made by hot melting asphalt, dispersing it in an aqueous solution containing an emulsifier in a fine particle state through mechanical action, forming an oil-in-water asphalt emulsion. In road construction and maintenance projects, emulsified asphalt can be used for road maintenance, bonding between road layers, bridge deck paving, permeable oil on cement-stabilized macadam foundation, slurry seal waterproof layer, etc. It has the advantages of cold construction, safety, environmental protection, resource conservation, energy conservation, extended construction season, and improved construction conditions. It plays a very important role in the construction and maintenance of municipal roads, especially in recent years, the improvement of the production level of emulsified asphalt has actively promoted the technological progress and promotion and application of emulsified asphalt. However, in the production and use of emulsified asphalt, undesirable phenomena such as crusting, flocculation, oil-water stratification, and agglomeration often occur, which brings unnecessary troubles to construction. To this end, the author conducted a large number of experimental studies from nine aspects, including emulsification equipment, emulsifier, base asphalt, pH value, temperature, storage temperature, mechanical action, freezing and melting, and long-term placement, and summarized the factors that affect the stability of emulsified asphalt. The analysis is as follows: