In order to study the role of HMGR in biosynthesis of rubber. 'Huazhong 6' were used in this study, and tThe full-length cDNA of EuHMGR was cloned from leaves and pericarp of 'Huazhong 6' based on the databases of Eucommia ulmoides genome and transcriptome，the sequence consists of 1773bp, which encoding of 590 amino acid residues .The real-time PCR method was used for evaulating the EuHMGR expression of leaves and pericarp at different developmental stages. It was found that the maximum expression amount of EuHMGR in pericarp was in mid May，while in leaves was in mid July. Besides, we useand the Soxhlet extraction method was used for analysising to analysis the rubber-content of leaves and pericarp in corresponding period. It showed that rubber-content of pericarp increased rapidly from mid April to late May, which of leaves showed a steady increase over time.Comparing the trend between the expression level of EuHMGR and the rate of rubber growth, It was found that the change of EuHMGR expression level in pericarp was similar to that of the rate of rubber growth at different developmental stages, on the contrary, in the leaves, theses tendency have no obvious correlation. Therefore，it was speculated that the expression of EuHMGR is related with the biosynthesis of rubber.