The high crystallinity of zeolite NaA were prepared by hydrothermal method based on the combination of calcined silico-manganese slag (Si-Mn slag) and fly ash. The influence of n(SiO2)/n(Al2O3), the concentration of NaOH, hydrothermal temperature and hydrothermal time on products were studied by single factor experiment. The results show that the zeolite NaA with good crystallinity and thermal stability can be synthesized at the condition of the mass ratio of calcined silico-manganese slag and fly ash=1∶1, n(SiO2)/n(Al2O3)=2.2, temperature of 90 ℃, alkalinity of 2 mol/L and reaction time of 4 h. Compared with the traditional synthesis of the zeolite NaA with fly ash as raw material, the addition of silico-manganese slag makes it a composite system, providing a new way for the resource utilization of silico-manganese slag.