The invention relates to a comprehensive utilization method of spice production waste residues and synthetic ammonia purge gas, which comprises the following steps: 1, adding water into basic magnesium chloride waste residues generated in spice production, heating, and hydrolyzing basic magnesium chloride to obtain turbid liquid of magnesium chloride and magnesium hydroxide, 2, adding hydrogen peroxide to oxidize and decolorize, and carrying out filter pressing separation to obtain a magnesium hydroxide filter cake, 3, adding water into the magnesium hydroxide filter cake, and pulping to obtain a magnesium hydroxide turbid solution, 4, introducing synthetic ammonia purge gas into the turbid liquid for carbonization reaction to obtain magnesium bicarbonate water containing magnesium bicarbonate, and 5, heating and pyrolyzing the heavy magnesium water to obtain basic magnesium carbonate turbid liquid, performing filter pressing to obtain a filter cake, and washing, drying and calcining the filter cake to obtain high-activity magnesium oxide. The method has the advantages that the problem of recycling of magnesium resources is solved, and the pollution of waste residues to soil and surface water and the influence of direct emission of carbon dioxide gas into the atmosphere on the ecological environment are avoided. By adopting the pressurized carbonization method, the carbonization time is shortened, the utilization rate of carbon dioxide is increased, the energy consumption is reduced, the equipment investment is reduced, and the economic and ecological benefits are remarkable.