By using industrial pseudo-boehmite prepared spherical alumina powder with sol - gel and spray granulation technology, the powder was calcined at different temperatures in the muffle furnace. SEM was used to observe the microstructure of the powder obtained. The phase composition of the powder calcined at different temperatures was probed with XRD. The size distribution of powder was tested by using mastersize. And integrated surface roughness tester was used to test the surface roughness of the workpiece. The results show that the shape of the powder prepared through spray granulation and calcination is spherical. In addition, as the temperature increases gradually, the phase changes from γ-Al2O3 into θ-Al2O3, and then into α-Al2O3. When the calcination temperature is too high, the power will bond with each other. If the time of heat preservation is prolonged, the powder will grow along the dense area. And when the powder has good crystallinity and more uniform size, its polishing performance is much better.