The partial cDNA of adipose triglyceride lipase (ATGL) was cloned (GenBank accession number HQ845211), and the homologous alignment was analyzed in grass carp Ctenopharyngodon idellus. The expression of ATGL gene in ten different organs was detected with the methods of qRT-PCR. The influence of dietary n-3 highly unsaturated fatty acids (n-3 HUFAs) on its temporal expression in hepatopancreas of grass carp was also studied. The results showed that the obtained cDNA sequence is 687bp in length, and its homology with human, cow, mice, large yellow croaker, long-jawed mudsucker and other species is 65%-75%. It is revealed that ATGL is widely expressed in heart, hepatopancreas, spleen, gills, kidney, muscle, intrapaneal fat body (IPF), brain, intestine, spermary, with the highest expression level observed in IPF. The expression level of ATGL gene in the feeding trial was increased significantly during the first and second weeks, and then appeared to have no difference compared with that of control group. Our results indicate that ATGL is mainly expressed in lipid highly metabolized and deposited tissues in grass carp, and dietary n-3 HUFAs influence the expression of ATGL gene in hepatopancreas, with the expression pattern described as rising at first, then going down to the normal level.