A novel flaky catalyst for synthesizing a dimmer acid ester consists of activated clay, a promoter and an adhesive pore-forming agent, wherein the activated clay accounts for 65-85 percent, the promoter accounts for 2-10 percent, and the adhesive pore-forming agent accounts for 13-25 percent. The preparation method for the catalyst comprises the following steps of: preparing the powder of the activated clay with a particle size of 150-250 meshes; mixing the raw materials evenly according to the partition ratio; tabletting and forming; drying the mixture at 105 DEG C; calcining the mixture at 300-400 DEG C; and cooling down and packaging the mixture. The method is simple and feasible. The catalyst which has good activity and high strength is easy to be separated from products with less products carried. In addition, the catalyst is easy to be regenerated.