The invention relates to a preparation method of a rotary-screen plain-colored high-gram-weight single-layer raising blanket. Suitable raw materials are selected and woven to obtain a grey cloth, thenslitting and pre-shaping are conducted, and pre-treatment is conducted; in the pre-treatment process, after the grey cloth is subjected to pre-drying, brushing, luster finishing and hot shearing, printing and dyeing parameters are adjusted according to the fact that the net gram weight of the product is high, rotary screen printing and dyeing equipment is adopted, an empty rotary net is utilizedas a color paste adding net and a permeation net, a permeation device is additionally arranged for printing and dyeing, the printing and dyeing effect is ensured, a drying and steaming integrated machine is adopted for color fixation, the color fixation effect is ensured, and the efficiency is improved; then the front and reverse sides of a semi-finished single-layer blanket are sequentially subjected to brushing, luster finishing, hot shearing, reverse side raising, brushing, and hot shearing again, and then cloth cutting and edge covering are conducted to obtain the finished product. The preparation method is reasonable in process and high in efficiency, and has the good printing and dyeing effect and high production and application value.