Gastric cancer (GC) is the fifth leading cancer in the world. The dysregulated expressions of the thrombospondin (THBS) family were reported to associate with GC, but their relations with tumor stage, prognosis, and correlations with tumor immunity have not been systematically reported. We used versatile public databases such as Oncomine, GEPIA, UALCAN, Kaplan-Meier Plotter, LinkedOmics, STRING, cBioPortal, TIMER, and TISIDB to analyze the expression and mutations of different in GC, along with their functional networks, survival analysis, and tumor-immune interactions. The mRNA levels of , and were significantly higher in the tumor tissues; the expression levels of , , and were higher in stages 2-4 than that of stage 1; patients with high expression of , , , and had poor OS; the genes correlated with were enriched in focal adhesion, glycosaminoglycan biosynthesis, ECM-receptor interaction, and hedgehog signaling pathway; and expression had significant correlations with tumor purity, and all the expression correlated with macrophage and dendritic cells infiltration. THBS2, THBS4, and COMP were potentially diagnostic markers for GC; THBS1, THBS2, THBS4, and COMP were potentially prognostic markers for GC; investigating the relations of THBSs and tumor immunology might help in immunotherapy of GC, while more studies are needed to confirm these results.