A technique for producing coal natural gas by utilizing crushed coal slag through gasification includes that part of crude coal gas containing CH4 produced by crushed coal slag through gasification receives sulfur tolerant shift, the other part of crude coal gas is conveyed in a sub-line and converges with the gas after sulfur tolerant shift to be cooled, the cooled gas is purified to remove CO2,H2S, naphtha and H2O and other impurities to obtain synthesis gas meeting the methane synthesis H/C ratio, the synthesis gas performs methane synthesis under the effect of methane conversion catalyst, and the methane-synthesis natural gas (SNG) is transmitted in long-distance pipeline network after compression and drying. The invention has the advantages of high gasification rate, high gasification intensity, low consumption and low water content of coal gas.