The invention discloses a method used for producing a pure-cotton napping fusible interlining with bright colors and convenient to operate. A production process comprises steps as follows: sewing, napping, refining, bleaching, dyeing, anti-shrinking finishing, bright powder point coating and mechanical pre-shrinking. According to the method, technological operation is convenient, water and energy are saved, pollution is reduced, product performance is excellent, the coating surface is bright, a fluffy nap layer is arranged on the back of the coating, the color fastness is higher than or equal to 4 levels, the content of free and hydrolyzed formaldehyde is lower than or equal to 35 mg/kg, and the dimensional stability to washing in warp and weft directions is in a range from minus 1.0% to plus 0.5%; after the napping fusible interlining is bonded with a garment material, the fabric feels full and thick.