Microalgae is the third generation of potential bio-energy resources,and the presence of grease in microalgae is mainly triacylglycerol.Diacylglycerol acyltransferase ( DGAT ) is a key rate-limiting enzyme in the control of TAG synthesis. DGAT is divided into DGAT1 , DGAT2 , DGAT3 and WS/DGAT .The DGAT of microalgae and higher plants was obtained from the database.The diversity and evolution of the four DGAT types and gene and protein structures was analyzed with phylogenetic methods.In order to further analyze the evolution of DGAT in microalgae,the positive selection sites were selected to estimate the selection pressure in the evolutionary process.Result showed that the genetic structure and protein structure of different DGAT types in microalgae were different.In the same DGAT type,the gene structure and protein structure of microalgae was different from that of other higher plants.It was found that microalgae did have different evolutionary processes with other higher plants.There was a positive selection sites of DGAT2 and WS / DGAT .Thepositive selection sites of DGAT1 and DGAT3 were not found.It will help us to decipher its functional role in plants and promote the research of renewable energy.