Over the past few years, gastric cancer prewarning and early theranostic system have achieved great advances. Gastric cancer theranostic strategies still focus on prediction and prewarning of early gastric cancer, early diagnosis and molecular imaging directed operation therapy, enhanced immunotherapy and killing gastric cancer stem cells to overcome multidrug resistance (MDR). Here we review the main advances in this field over the past few years, explore the clinical translational prospects, and discuss the concepts, issues, approaches, and challenges, with the aim of stimulating a broader interest in developing gastric cancer prewarning and early theranostic system and promoting clinical translation.