NOVELTY - Producing composite fertilizer using low grade phosphorite and dolomite involves: (A) adding concentrated sulfuric acid to the wet phosphorite ore, to obtain phosphoric acid and calcium hydrogen phosphate; (B) after 2 hours adding dolomite, adding water to wet the dolomite, treating with concentrated sulfuric acid to release the water-soluble calcium and magnesium; (C) crushing mixture of step B), then adding ammonium phosphate and then adding molten ammonium nitrate; and (D) granulating the slurry obtained in step C) followed by cooling and packaging the finished product.    USE - For producing composite fertilizer using low grade phosphorite and dolomite (claimed).    ADVANTAGE - Compared with the existing technology, the present method provides the following beneficial effects: 1) the method uses low grade phosphate ore and dolomite using tower granulation method for producing high-efficient compound fertilizer where waste gas production is little, the process is convenient and there is no waste solid generated as a result it is environmentally friendly; 2) use of dolomite provides fertilizer comprising calcium, magnesium and sulfur that solves the problem of the current market fertilizer that do not have all the three element content; 3) the process of treating ore with an acid in the reaction process, does not need to evaporate water, which saves energy by adding mineral reactant and 4) the quality of the product is stable, to consumption and enables large-scale production.    DETAILED DESCRIPTION - Producing composite fertilizer using low grade phosphorite and dolomite involves: (a) adding concentrated sulfuric acid to the wet phosphorite ore, to obtain phosphoric acid and calcium hydrogen phosphate, then carrying out recycling and treating the tail gas; (b) after 2 hours adding dolomite, adding water to wet the dolomite, treating with concentrated sulfuric acid to release the water-soluble calcium and magnesium; (c) crushing mixture of step b) using a crusher, then adding ammonium phosphate, with elevator bucket, sending it to a prilling tower, heating to 80 degrees C, adding molten ammonium nitrate solution, and stirring the solution; (d) granulating the slurry obtained in step (c) by controlling the temperature at 140-160 degrees C, and using a granulator with air under convection, where the granulating tower shrinks inwards round particle, followed by cooling and packaging the finished product.