The characteristics of La2O3 catalysts with three different supports (BaCO3, MgO, and ZnO), two different alkaline metal promoters (Na2O and Na2CO3), and a china clay have been investigated. The relationship of the surface basicity of the support to the activity and selectivity af the catalyst were studied by TPD. The results showed that the surface basicity of these three supports decreased in the following order : BaCO3 > MgO > ZnO. The choice of Na2O as a promoter in La2O3/(BaCO3 or MgO) had a better effect than the choice of Na2CO3. The Na2O promoter could increase not only the catalytic activity and the C-2 selectivity, but also lower the optimal reaction temperature, Addition of 15% clay into the La2O3-alkaline metal catalysts could increase the strength of the catalyst and lower the optimum reaction temperature.