The differential diagnosis of gastric submucosal tumors by endoscopic ultrasound is currently suboptimal. Needle-based confocal laser endomicroscopy (nCLE) is a novel endoscopic technique, which is compatible with the 19-gauge FNA needle. Under endoscopic ultrasonography (EUS) guidance, nCLE enables real-time in vivo imaging of lesion tissues at cellular and subcellular levels. This study aimed to describe nCLE interpretation criteria for the characterization of gastric submucosal tumors, with histopathological correlation, and to perform the validation of these criteria.