Two organoselenium compounds, both of which were modified with two primary amine groups, were designed and synthesized to mimic the catalytic properties of glutathione peroxidase (GPx). It was demonstrated that the catalytic mechanism of the diselenide organoselenium compound (compound 1) was a ping-pong mechanism while that of the selenide organoselenium compound (compound 2) was a sequential mechanism. The pH-controlled switching of the catalytic activities was achieved by controlling the formation and dissociation of the pseudorotaxanes based on the organoselenium compounds and cucurbit[6]uril (CB[6]). Moreover, the switching was reversible at pH between 7 and 9 for compound 1 or between 7 and 10 for compound 2.