Solvent extraction is an economically efficient method widely used in the purification of wet phosphoric acid. In this study, a microchannel was applied to promote the mixing and purification of phosphoric acid during continuous production. For this aim, solvent extraction was conducted to purify phosphoric acid via methyl isobutyl ketone/tri-butyl phosphate mixtures. Additionally, the Box-Behnken design method was used to survey the solvent extraction process. The effect of various operational parameters such as solvent concentration (45– 65 %wt. ), temperature (18-28˚ C), and organic/aqueous phase ratio (2: 1– 6: 1) at a constant flow rate of 70 mL/L was examined. Experimental results indicated that the microchannel at the residence time of 6. 85 min could promote the extraction percentage of and sulfate removal of more than 98% and 60%, respectively, compared to the batch extractor.