Gibberellic acid is a typical plant growth regulator, which has the efficacy of increasing yield and fruit preservation for crops. The preparation process of gibberellic acid dry flowable is still lacking systematic exploration, and the fruit preservation test of this preparation on citrus still needs to be verified. The study was aimed to investigate the effect of the wet grinding process of sand mill on the performance of gibberellic acid suspension slurry and to determine the performance of dry flowable prepared by spray drying. The 3% gibberellic acid dry flowable was prepared by the wet sand mill and pressure spray drying equipment, and the final process was screened according to the determination of particle size, viscosity, the retention rate of gibberellic acid content, and other performance indexes of the suspension concentrate through the optimization of the number of wet grinding times, the wet grinding speed, and the size of the diameter of zirconia beads used for wet grinding. The effect of 3% gibberellic acid dry flowable on citrus fruit set, fruit thickness, single fruit weight and soluble solids were tested in field efficacy test. The results showed that the optimal grinding process was 1 mm in diameter of the zirconium beads used for grinding, the grinding speed was 2500 r/min and grould twice. The viscosity of the suspension concentrate before spraying was lower than 200 mPa/s, and the particle size was about 2 µm, and the particle size of the suspension concentrate after spraying was about 3 µm after rehydration, and the retention rate of gibberellic acid was more than 90% after this grinding process, and the low viscosity of the slurry could meet the production requirements. The 3% gibberellic acid dry flowable produced by this process has high suspension rate (>90%), fast wetting speed (10 s), high retention rate of gibberellic acid, and the performance indexes are in accordance with the regulations, and there is no precipitation of suspension slurry during the production process. The results of the field trial showed that the spraying of gibberellic acid dry flowable increased the transverse and longitudinal diameter of the citrus single fruit, the thickness of the peel decreased, the weight of the single fruit increased, the soluble solids increased, and the fruiting rate of the planting area increased. The results provide theoretical support for the industrial production of gibberellic acid dry flowable, and the field trial of gibberellic acid dry flowable prepared in this study in citrus trees can provide reference for the application of gibberellic acid in citrus fruit trees.