Abstract: Prolyl hydroxylase（PHD） is a key enzyme in collagen synthesis, involved in the triple helix structure stability of collagen. In order to explore the expression of phd in different tissues of grass carp（Ctenopharyngodon idella） and its role in collagen synthesis, the full length 2 175 bp cDNA sequence of grass carp phd gene was obtained by the PCR amplification and RACE method, including a 168 bp 5′-end untranslated region, a 933 bp 3′-end untranslated region and a 1 074 bp open reading frame encoding 358 amino acids. The molecular weight of PHD protein is 39.773 kDa, and it is a hydrophilic protein without signal peptide and transmembrane region. Compared with BLAST alignment on NCBI, the amino acid sequence of grass carp PHD has a high homology with other fishes, moreover, the identity with Megalobrama amblycephala is 95.17%. The evolutionary analysis showed that PHD from grass carp had the closest relationship with that from Megalobrama amblycephala, and the furthest relationship with that from humans, mice and cattle. Tissue differential expression analysis showed that phd gene had the highest expression in the foregut, then in the brain, kidney, blood, heart, liver, gills, muscle, skin, and the lowest expression was observed in the spleen. When grass carp were fed diet containing 2% Eucommia ulmoides for 4 weeks and 8 weeks, the expression of phd was significantly promoted in the muscle, skin, heart and foregut. The present results can provide a scientific basis for studying the acting mechanism of prolyl hydroxylase in collagen formation of fishes.