Cluster of differentiation 90 (CD90) (Thy-1) plays important roles in the oncogenesis in various types of malignancies. In the present study, we investigated the expression of CD90 in gastric cancer (GC) tissues by q-PCR, immunohistochemistry (IHC), and western blot technologies. The results showed that CD90 was overexpressed in gastric cancer tissues compared with the level in the adjacent non‑cancerous tissues. To explore the possible mechanism of CD90 in GC, we elucidated the effect of CD90 on the apoptosis of AGS gastric cancer cells, and found that a considerable decrease in apoptotic cells was observed for AGS cells with CD90 overexpression. Meanwhile, the rate of apoptotic cells was increased in the AGS cells with CD90 interference (siCD90) compared with that in the AGS cells. Cell apoptosis is closely related to a reduction in mitochondrial membrane potential (ΔΨm) and an increase in intracellular reactive oxygen species (ROS) and calcium ion (Ca2+) concentrations. Our results showed that overexpression of CD90 in the AGS gastric cancer cells led to an increase in ΔΨm and a decrease in intracellular ROS and Ca2+ concentrations. At the same time, siCD90 reduced ΔΨm and the increase in intracellular ROS and Ca2+ concentrations. Furthermore, we identified and confirmed that CD90 functions by modulating the expression level of secreted protein, acidic, cysteine‑rich (osteonectin) (SPARC) in vitro through LC‑MS/MS analyses and western blot technology. In summary, our results suggest that CD90 is upregulated in gastric cancer and inhibits gastric cancer cell apoptosis by modulating the expression level of SPARC protein.