The invention belongs to the technical field of ore dressing and discloses an ore dressing process for reducing the content of silicon dioxide in iron ore concentrate. The ore dressing process includes: step one, crushing, to be more specific, crushing low-grade magnetic iron ore into size smaller than 20mm, and performing high-pressure rolling, superfine grinding and sieving and full-closed wet pre-separation to obtain rough concentrate in size smaller than 3mm; step two, ore grinding and magnetic separation, to be more specific, to be more specific, performing two-stage ore grinding, gradingand low-intensity magnetic separation; step three, fine sieving, to be more specific, feeding the magnetically separated rough concentrate into a fine sieve for sieving, and then returning materialson the sieve to a two-stage grinding system, wherein the sieve mesh size is 0.075-0.1mm; step four, feeding sieved powder into a wash mill, and concentrating to obtain washed concentrate; step five, magnetic desliming, to be more specific, subjecting the washed concentrate to concentration in a magnetic desliming tank to obtain final concentrate, wherein the SiO2 content is reduced to 3.5% or below. After two-stage grinding and low-intensity magnetic separation, two-stage continuous concentration is performed through the wash mill and the magnetic desliming tank, so that the problem of high SiO2 content of the ore concentrate is solved while quality improvement and impurity reduction of the ore concentrate are realized.