Agropyron cristatum (2n = 4x = 28, PPPP), which harbours many high-yield and disease-resistance genes, is a promising donor for wheat improvement. Narrow genetic diversity and the trade-off between grain weight and grain number have become bottlenecks for increasing grain yield in wheat. In this study, a novel translocation line, WAT650l, was derived from the chromosome 6P addition line 4844-12, which can simultaneously increase both grain number per spike (GNS) and thousand-grain weight (TGW). Cytological analysis and molecular marker analysis revealed that WAT650l was a 5BL.5BS-6PL (bin 12- 17) translocation line. Assessment of agronomic traits and analysis of the BC4F2 and BC5F2 populations suggested that the 6PL terminal chromosome segment in WAT650l resulted in increased grain number per spike (average increased by 14.07 grains), thousand-grain weight (average increased by 4.31 g), flag leaf length, plant height, spikelet number per spike and kernel number per spikelet during the two grow-ing seasons of 2020-2021 and 2021-2022. Additionally, the increased GNS locus and high-TGW locus of WAT650l were mapped to the bins 16-17 and 12-13, respectively, on chromosome 6PL by genetic pop-ulation analysis of three translocation lines. In summary, we provide a valuable germplasm resource for broadening the genetic base of wheat and overcoming the negative relationship between GNS and TGW in wheat breeding.& COPY; 2022 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).