The isotropic Pr-doped SrFe12O19 powders have been synthesized by mechanical milling and subsequent hear treatment. The effects of Pr3+ doping concentration and annealing condition on the microstructure and magnetic properties have been systematically investigated. It is found that the Pr3+ doping results in the increase of the temperature for the formation of hard magnetic compounds. The Curie temperature of PrxSr1-xFe12O19 samples keeps constant with the variation of composition of the sample; however, it decreases slightly with the increase of annealing temperature. The addition of a small amount of Pr3+ in the samples is beneficial to the improvement of coercivity, but accompanying with the deterioration of magnetization. The effect of annealing temperature on magnetic properties is different for the samples with different compositions.