Objective To explore the effects of celecoxib, a selective COX-2 inhibitor, on the expression of NHE1 and intracellular pH (pHi) of SGC-7901 human gastric carcinoma cells. Methods Human gastric carcinoma cell line SGC-7901 was used as research object. MTT method was used to detect the celecoxib's depressant effect on the proliferation of SGC-7901 cells after intervening with different concentrations of celecoxib (5, 12.5, 25, 50, 75, and 100 μmol/L) for different time. Western blot was applied to detect influence of different concentrations of celecoxib on NHE1 expression in SGC-7901 human gastric carcinoma cells. On this basis, pHi of SGC-7901 cells was tested by BCECF-AM immunofluorescence. Results Celecoxib could effectively inhibit the proliferation of SGC-7901 human gastric carcinoma cells. And within a certain concentration range, the inhibitory action on SGC-7901 cells increased with the increase of celecoxib concentration. It also increased with the extension of explosion time while at the same concentration (P<0.05). Different concentrations (except 5 μmol/L) of celecoxib could down-regulate the expression of NHE1 in SGC-7901 cells, which was concentration dependent (P<0.05). The pHi of SGC-7901 cells that were not intervened with celecoxib is alkaline. Compared the pHi of cells in control group, the pHi of SGC-7901 cells decreased significantly after intervening with different concentrations of celecoxib (except 5 μmol/L) for 24 h (P<0.05). And the decrease of pHi was also concentration dependent (P<0.05). Conclusion Celecoxib may inhibit the growth of SGC-7901 cells through down-regulating the expression of NHE1 and declining the pHi.