Considerable concentrations of circulating nucleic acids have been reported in peripheral blood from cancer patients. These circulating nucleic acids bear a variety of tumor-specific information and potentially represent a stable source of non-invasive tumor biomarkers. The assessable genetic and epigenetic changes of circulating nucleic acids include DNA mutations, copy number alterations, abnormal methylation and disruption of microRNA. Such alterations reflecting molecular characteristics of tumor tissues, provide a new clue for noninvasive, real-time and monitoring test. In the present article, the main findings of research status related to the utility of circulating nucleic acids for early diagnosis, prognosis and monitoring of gastric cancer are reviewed. In addition, the advantage, the examination technique and the application prospection of circulating nucleic acids as tumor markers are also reviewed.