The invention relates to an oil extraction process for oil fields, in particular to a multi-crack fracturing control method for medium-depth coal beds. The method comprises six steps of 1) preparation of a filtrate reduction fracturing fluid; 2) utilization of a high-pressure pump set; 3) utilization of a high-pressure pump set; 4) utilization of a high-pressure pump set; 5) phased utilization of a prepad liquid; and 6) ending of work. According to the multi-crack fracturing control method, prior conventional active-water sand fracturing method is changed through theoretical analysis and on-site verification, and the filtrate reduction fracturing fluid, the prepad liquid variable displacement technology, a multi-stage particle size slug technology, a reasonable mortar-sand ratio raising technology and the like are used, accordingly, difficulties such as large filter losses, poor sand carrying capabilities and excess leak-off of the fracturing liquid and high construction pressure during opening of natural cracks are overcome. Multi-crack is effectively prevented and treated through the means of the filtrate reduction fracturing fluid, and the prepad liquid variable displacement technology and the multi-stage particle size slug technology, so that the construction pressure is reduced, smooth adding of a propping agent is guaranteed, and the fracturing construction success rate is improved.