High molecular weight glutenin subunits (HMW-GSs) are key determinants for the end-use quality of wheat. Chinese wheat landraces are an important resource for exploring novel HMW-GS genes to improve the wheat baking quality. Two novel Glu-1Dy HMW-GSs (designated as 1Dy12.6 and 1Dy12.7) were identified and cloned from two Chinese wheat landraces Huazhong830 and Luosimai. The 1Dy12.6 and 1Dy12.7 subunits were deposited as the NCBInr Acc. No KR262518, and KR262519, respectively. The full open reading frames (ORFs) of 1Dy12.6 and 1Dy12.7 were 2022 bp and 1977 bp, encoding for proteins of 673 and 658 amino acid residues, respectively. Each contains four typical primary regions of HMW-GSs (a signal peptide, N- and C-terminal regions, and a central repetitive region). Their deduced molecular masses (70,165 Da and 68,400 Da) were strikingly consistent with those identified by MALDI-TOF-MS (69,985Da and 68,407 Da). The 1Dy12.6 is the largest 1Dy glutenin subunits cloned in common wheat up to date, containing longer repetitive central domains than other 1Dy encoded proteins. In comparison with the most similar active 1Dy alleles previously reported, the newly discovered alleles contained a total of 20 SNPs and 3 indels. The secondary structure prediction indicated that 1Dy12.6 and 1Dy12.7 have similar proportion of α-helix, β-turn, and β-bend to those of 1Dy10 (X12929). The phylogenetic analysis illustrated that the x- and y-type subunits of glutenins were well separated, but both 1Dy12.6 and 1Dy12.7 were clustered with the other Glu-1Dy alleles. Our results revealed that the 1Dy12.6 and 1Dy12.7 subunit have potential to strengthen gluten polymer interactions, and are valuable genetic resources for wheat quality improvement.