The invention belongs to the technical field of coal mine fire prevention and extinguishment, and discloses a fire preventing and extinguishing gel preparation method and a coal mine fire preventing and extinguishing method. The fire preventing and extinguishing gel is prepared from, by mass, 1%-2% of carboxymethyl cellulose, 4%-5% of a cross-linking agent, 4%-5% of sodium bicarbonate, 4%-5% of a water glass diluted solution, 0.1%-0.3% of a pH regulator and water. The preparation method comprises the following steps: dissolving carboxymethyl cellulose in distilled water, heating and fully stirring, then adding aluminum citrate into a solution, introducing nitrogen for protection, and reacting to obtain a first solution; raising the temperature, continuously adding glucolactone into the first solution, and continuously stirring and reacting to obtain a second solution; adding sodium bicarbonate into the second solution, uniformly stirring, adding the pH regulator, and adjusting to obtain a third solution; dissolving water glass in distilled water, mixing, dropwise adding into the third solution, and reacting to obtain a final product. The coal storage time is prolonged, and the safety production efficiency of a coal mine is improved.