Variations of main biochemical components, such as tea polyphenol, total catechins, free amino acid, caffeine, five catechins (EGC, C, EGCG, EC, ECG), and catechin oxidation products (TF, TR and TB) during the primary processing of Pekoe Oolong tea were investigated. The results showed that the water extract content was higher than the national standard. The contents of tea polyphenol and total catechins obviously decreased. The free amino acid contents were increasing in the primary processing. The contents of caffeine and?soluble?sugar decreased. In five catechins investigated, EGCG and ECG varied acutely. The contents of TF, TR and TB increased in the primary processing and the TR/TF ratio in the raw tea was 12.10 approximately. In addition, the main biochemical components in Rizhao Pekoe Oolong tea and black tea and the components in Oolong tea from Fujian and Taiwan were compared to study the characteristics of Rizhao Pekoe Oolong tea.