As the most basic feature of service industry，interaction is defined as the mutual action and influence among various objects． After reviewing the recent researches of service brand equity，twelve main interaction factors among service enterprises，employees and customers are drawn out． Then an analytical framework of service brand equity based on multidimensional interaction is established，and an exploratory empirical study in four service industries of Guangzhou is conducted，where the influence of those twelve factors on service brand equity is presented through gray relation analysis． It is proved that multidimensional interaction is the root cause of the swing of service brand equity，also the features of service enterprise’brand building， which is still in the primary stage in China，is reflected．