Peach blossom comes from the flower of Prunus persica (L.) Batsch, which is used as herbal tea and medicine in China and Korea. It could promote defecation and alleviate the abdominal pain. In this paper, the methods, ultra-performance liquid chromatography (UPLC) method coupled with electrospray ionization hybrid linear trap quadrupole orbitrap mass spectrometry (LTQ OrbitrapMS) and UPLC system coupled with a diode array detector (DAD), were developed for the qualitative and quantitative analysis of the flavonoids and phenolic acids in peach blossoms. Eight standards were divided into 3 types according to their basic skeletons: phenolic acids, quercetin-type flavonoids, and kaempferol-type flavonoids. The MSn fragmentation behaviors and diagnostic ions of these 3 types of compounds were proposed to aid the structural identification of components in peach blossom extract. By extracting the diagnostic ions from the mass spectrum in negative mode, a total of 25 compounds, including 8 phenolic acids and 17 flavonoids, were screened out. Among these compounds, 5 compounds (chlorogenic acid, ferulic acid, rutin, hyperoside, and isoquercetrin) were quantitated by UPLC-DAD. The linearity, precision, accuracy, limit of detection, and limit of quantitation were validated for the quantification method. The validated method was applied to assay 9 batches of peach blossoms from different regions. This study was the first report on the systematic qualitative analysis of compounds in peach blossom, providing insights into the quality control of peach blossom.