Dimer acid, usually dimeric fatty acid is a complex mixture of ingredients; it is named because the main components contain two carboxylic acid groups. It is produced from the use of unsaturated fatty acids such as oleic acid and linoleum acid obtained by mutual polymerization. Dimer acid has excellent thermal stability, and in a wide temperature range to maintain liquidity. It has been already widely used in the synthesis printed circuit board material, ink manufacturing, rocket motor materials. It is high purity dimer acid as light yellow viscous liquid, the lower purity dimer acid as reddish brown viscous liquid. The current commonly used vegetable oil as a raw material in the catalyst foot high temperature and pressure under the reaction crude, and then by molecular distillation treatment are pure.