In order to study the influence of acidity on leaching characteristics of cationic emulsified asphalt in solution, the immersiom experiments of cationic emulsified asphalt specimens in acid solution with different pH values were designed. Technical indexes, such as suspended solid particles, chemical oxygen demand, total hardness and cationic emulsifier content in immersion solution were studied with chemical analysis methods, such as spectrophotometric method, titrimetric method and weight loss method; and the influence of acidity on cationic emulsifier, asphalt component and Ca2+, Mg2+leaching characteristics was investigated. The results show that the emulsifier, asphalt components, Ca2+and Mg2+in cationic emulsified asphalt can all be leached. The leached amount of asphalt component and cationic emulsifier is great. The higher the acidity of immersing solution, the greater the leached amount. However, the acidity of immersion solution has less influence on the leaching of the emulsifier. Besides, the leached amount of Ca2+and Mg2+is less. The acidity of immersion solution has almost no influence on the leached amount of Ca2+and Mg2+.