An alkanolamine, N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine, is used as an organic structure-directing agent (OSDA) to synthesize aluminiophosphate (AlPO-5) and silico-aluminophosphate (SAPO-5 and -34) molecular sieves. The phase selectivity among them is feasible by optimizing experimental conditions wherein high concentrations of OSDA and silicon source favor the formation of SAPO-34. In addition, the phase selectivity between SAPO-5 and SAPO-34 is examined in detail by altering the chemical compositions of the raw materials.