BaSO4 microspheres with a uniform diameter have been prepared in the presence of EDTA•2Na. The structures of BaSO4 microspheres were characterized by XRD, FTIR, XRF，SEM and particle size analyzer. The factors of EDTA•2Na dosage, the concentration of BaCl2 and Na2SO4, reaction temperature and pH adjusted once again were investigated. The prepared conditions are: c(BaCl2)=1.0 mol/L, n(EDTA•2Na):n(BaCl2):n(Na2SO4)=1:1:1，reaction temperature was 55 ℃ and pH was 9.0. Results showed that the particles are BaSO4. Monodisperse microspheres with the diameter ranging from 1.3 to 0.8 μm account for 47.01% of all particles. The yield of BaSO4 microspheres was 74.15%. When pH is adjusted once again to 7.0, the yield of BaSO4 increases from 74.15% to 87.88%. Meanwhile, BaSO4 diameter differs from sub-micron scale to 2 μm, which decreases the dimensional uniformity.