Golgi phosphoprotein 2 (GOLPH2) is a very important biomarker in a variety of diseases. Its biological function is not clear, particularly in gastric cancer. To investigate the role of GOLPH2 in human gastric cancer, and determine its effect on the Th1 lymphocyte response, its expression and that of IL-12A were measured by real-time PCR and immunohistochemistry. The relationship between GOLPH2 and IL-12A was analysed statistically. The effect of GOLPH2 on the Th1 lymphocyte response was investigated with an in vitro co-culture system. The results showed that in human gastric cancer, the expression of GOLPH2 was significantly higher and the expression of IL-12A was lower than in normal gastric mucosal tissues, and the expression levels of GOLPH2 and IL-12A were negatively correlated. In addition, obvious down-regulation of the Th1 response was observed when lymphocytes were co-cultured with gastric cancer SGC7901 cells over-expressing GOLPH2. GOLPH2 down-regulated the expression of IL-12A, and inhibited the expression of TNF-${alpha}$ and IFN-${gamma}$. The results indicated that GOLPH2 down-regulates the Th1 response via suppression of IL-12A in human gastric cancer, and this might provide a target for the prevention and treatment.