The invention relates to an iron-containing wastewater pretreatment device. The pretreatment device comprises an adjusting tank, a reduction reaction tank, a crystallization settling tank, a quicksand filtering tank and a water storage tank which are sequentially communicated with each other, wherein the adjusting tank comprises an adjusting tank water inlet pipe and an adjusting tank water outlet pipe; a reduction reaction tank water inlet pipe is arranged at the middle upper part of the reduction reaction tank, a reducing agent adding and measuring system is arranged at the upper part of the reduction reaction tank, a reduction reaction tank stirrer is arranged in the middle of the reduction reaction tank, and a reduction reaction tank water outlet pipe is arranged at the bottom of the reduction reaction tank; the crystallization settling tank comprises an overflowing weir and a water outlet pipe, the overflowing weir is connected with a crystallization settling tank water outlet pipe, and the water outlet pipe is connected with the crystallization settling tank water inlet pipe; and the quicksand filtering tank is provided with a quicksand filtering tank water inlet pipe and a quicksand filtering tank water outlet pipe and comprises a water distribution region, a sand washing region and a sand filtering region, the quicksand filtering tank water outlet pipe is used for draining treated water; and water treated in the quicksand filtering tank enters the water storage tank.