The present invention relates to aluminate coupling agents, their synthesis and appliations. metallic aluminum is reacted with lower alcohols, then reacted with selected longer chain alcohols, phenols, carboxylic acids etc., satisfied the coordination num- be l of aluminum to give aluminate coupling agents having good hydrolytic stability and lower associativity. They can be used directly as typical coupling agents in processing of composition products such as plastics, rubber, coatings and laminates etc., and as adhesive promoter or primer to treat fillers, pigments and various materials in order to improve the processing and the quality of products, to increase the dosage of filler, to develop new products, to reduce energy consuming and cost of products.