The influences of the oxidant($O_2;and;O_3$) on the FeOOH formation were studied with fixed $FeSO_4{cdot}7H_2O$ concentration (0.5M) and NaOH equivalent ratio(0.5). The characteristics of the synthesized powders were evaluateed by XRD, and equantitative phase analysis. $alpha-FeOOH$ (Geothite) and/or $gamma-FeOOH$ was promoted when $O_3$ was used as a oxidant which is stronger oxidizing agent than $O_2$.