Adiponectin is an abundantly secreted adipokine from the adipose tissue of mammals, and plays central roles in the regulation of glucose and lipid metabolism. The biological function of adiponectin is mediated by at least two putative receptors (AdipoR1 and AdipoR2). In order to investigate the molecular regulatory mechanisms of lipid metabolism and liver lipid accumulation in fish, the full-length cDNA sequences of adiponectin receptor1-B (AdipoR1-B) from grass carp has been identified by rapid amplification cDNA ends (RACE), and the structural features of the gene and its encoded protein have been analysed through bioinformatics methods. Using the method of real-time PCR, the expression pattern of AdipoR1-B in nineteen different tissues of grass carp has been studied, and the expression levels of AdipoR1-B in the liver of grass carp under different nutrient conditions with high carbohydrate (H-CHO), high lipid (H-LIP) and high carbohydrate & high lipid (H-CHO & H-LIP) have been studied. The result revealed that the obtained cDNA of AdipoR1-B in grass carp was 2186 bp in length, which consisted of a 1122 bp open reading frame (ORF), encoding 373 amino acids. Alignment based on amino acid sequences showed that grass carp AdipoR1-B had a homology of 81.0%-94.1% to its counterparts in other fishes. Phylogenetic analysis showed that grass carp AdipoR1-B clustered with that of zebrafish. The AdipoR1-B mRNA could be detected in all the examined tissues of grass carp. But the expression level in liver was the highest, followed by central nervous system and red muscle. Compared with the control group, the expression levels of AdipoR1-B in the H-LIP and H-CHO & H-LIP groups had increased significantly. This result suggested that adiponectin may improve the utilization of lipid in grass carp and it may be involved in the lipid metabolism process in fish. The research data can enrich the knowledge of lipid metabolism regulation mechanism of fish, and lay a foundation for the further functional research of the adiponectin/AdipoRs system in fish.