Oral cavity cancer is one of the most common cancer worldwide and oral cavity squamous cell carcinoma (OSCC) accounts for up to 90 percent of oral cancers. In Taiwan, OSCC is the fifth most common malignancy of male and causes more than 250 deaths per year. The poor outcome of OSCC patients is principally ascribed to the fact that this disease is often advanced at the time of diagnosis, suggesting that early detection and prevention of OSCC are urgently needed to reduce the cancer burden. Analysis of cancer-related body fluids is one of promising approaches to identify cancer-related molecules and biomarker candidates. To identify salivary biomarkers of OSCC, salivary samples of OSCC patients, individuals with oral potentially malignant disorders (OPMD), and healthy volunteers were collected. With isobaric tags for relative and absolute quantitation (iTRAQ)-based mass spectrometry (MS) analysis, 1838 proteins were identified. The levels of 102 proteins are found to be elevated in the saliva samples of OSCC patients compared to that of OPMD and healthy groups. To improve the feasibility of biomarkers, we used a two-phase verification to measure these candidates. Among them, salivary levels of AHSG, CFH, FGA, and SERPINA1 were determined to be significantly higher in the OSCC patients than in the healthy or in the OPMD group with both of MRM-MS and ELISA. Furthermore, the levels of these proteins were highly related to tumor size, lymph-node metastasis, and cancer stages. The results of this study not only provides a powerful strategy for verification of biomarker candidates, but also suggested that AHSG, CFH, FGA, and SERPINA1 could act as salivary biomarkers for OSCC detection.