Cultivated and wild Rosa roxburghii Tratt were investigated to determine the intrinsic causes of the quality differences. The cultivated fruit, Guinong No. 5 (GNNF) was larger, heavier, and had less color difference. Its juice contained higher levels of soluble solids and tannins. The wild variety (WRRT) had higher concentrations of condensed tannins, polyphenols and flavonoids. Artificial sensory and electronic taste tests indicated GNNF had a lower astringent and bitter taste compared to WRRT. A total of 80 flavour substances were identified by gas chromatography‒mass spectrometry (GC-MS). The relative contents of esters, organic acids, ketones, alcohols, aldehydes and aromatic hydrocarbons were higher in GNNF than in WRRT. Caffeylalcohol, catechin, quinidine, pantothenic acid and five bitter amino acids were high in GNNF. The high contents of bitter substances such as limonin, daidzein, and rutaevin were responsible for the quality differences between WRRT and GNNF.