The purple flowers and white pink flowers of Rhododendron latoucheae were selected during the flowering process including all-green stage, showing red stage, early flowering stage and full blooming stage. Determination of metabolites of Rhododendron latoucheae petals was conducted based on ultra performance liquid chromatography- tandem mass spectrometry(UPLC-MS/MS). The differential metabolites were screened by orthogonal partial least squares discriminant analysis(OPLS-DA), and the key differential metabolites associated with flower color were screened by enrichment analysis using the KEGG database, and the correlation analysis was used to verify the correlation between the key metabolites and flower color of Rhododendron latoucheae. The results showed that a total of 1057 metabolites were detected in the petals of Rhododendron latoucheae, including 243 differential metabolites, which were significantly enriched in flavonoid and anthocyanin metabolic pathways, and the content of malvidin-3-O-glucoside in the petals of purple-flowered Rhododendron latoucheae was much higher than that of white-pink-flowered Rhododendron latoucheae. Therefore, it is speculated that malvidin-3-O-glucoside is the key anthocyanin for the purple color of Rhododendron latoucheae petals. Dihydromyricetin and gallocatechin affect the synthesis of anthocyanins through the flavonoid synthesis pathway, which in turn affects the flower color of Rhododendron latoucheae.