Rape straw is a waste product of rapeseed oil production that can be processed for use by burning. This study examined the processing of rape straw ash into compound fertilizers containing phosphorus, potassium, calcium, magnesium, and microelements by granulation using additives from sugar factories, such as sugar factory lime and molasses. Rape straw ash was examined by chemical analysis, differential scanning calorimetry- thermogravimetry, infrared spectroscopy, and x-ray diffraction analysis. The optimum parameters of compound fertilizer granulation and the main physicochemical properties of the product, such as particle size distribution, moisture content, pH, and particle-crushing strength were determined using standard methods. The results of our investigation show that compound fertilizers of 0-6-21-23CaO-2MgO grade can be obtained from rape straw ash using sugar factory lime and molasses.