The Qianjiangsaurus holotype specimen, CLGRP V00016, was discovered by a paleontological expedition associated with the Chongqing Bureau of Geological and Mineral Resource Exploration and Development during the winter of 2022.

[1] After being announced in August 2024 in a non-finalized preprint, Dai et al. (2025) described Qianjiangsaurus changshengi as a new genus and species of hadrosauroid dinosaurs based on these fossil remains.

[1] The prepubic process of the pubis is fan-shaped, with a length:height ratio of about 0.79, representing the single autapomorphy (unique derived trait) identified in the holotype.

[1] In their phylogenetic analyses, Dai et al. (2025) recovered Qianjiangsaurus as the sister taxon to the Mongolian Plesiohadros,[3] with these taxa as late-diverging members of the Hadrosauroidea outside of the Hadrosauridae.

Their results are displayed in the cladogram below:[1] Iguanodontidae Jinzhousaurus Equijubus Sirindhorna Xuwulong Zuoyunlong Probactrosaurus Eolambia Jintasaurus Yunganglong Levnesovia Tanius Bactrosaurus Gilmoreosaurus Gobihadros Nanningosaurus Claosaurus Plesiohadros Qianjiangsaurus Telmatosaurus Tethyshadros Eotrachodon Zhanghenglong Hadrosaurus Lambeosaurinae Saurolophinae The discovery of Qianjiangsaurus provides further support for several faunal similarities between the Zhengyang Formation of China and the Djadokhta and Baruungoyot formations of Mongolia.