A method for measuring the components and calorific value of a coal gas comprising 6 components being CO, CO 2 , CH 4 , C n H m , H 2 and O 2 with a range of up to 40% CO, 30% CO 2 , 20% CH 4 , 5% C n H m , 20% H 2 and 25% O 2 , comprising the steps of: - measuring a volume concentration of H 2 (T H2 ) in the coal gas by using a thermal conductivity detector (TCD), - measuring a volume concentration of O 2 in the coal gas using an electrochemical detector (ECD), and - calculating the calorific value of the coal gas via measured and revised volume concentrations of various gases; the method further comprising the following steps: 1) measuring volume concentrations of CO, CO 2 , CH 4 , and C n H m in the coal gas, represented by T CO , T CO2 , T CH4 , and T CnHm , respectively, in the coal gas using non-dispersive infrared (NDIR) technology; 2) calculating a revised volume concentration of C n H m (R CnHm ) using the equation R CnHm = T CnHm -A×T CH4 , in which T CnHm and T CH4 represent the volume concentrations of C n H m and CH 4 measured with NDIR, respectively, and A is 0.02868; 3) calculating a revised volume concentration of H 2 (R H2 ) using the equation R H2 = T H2 -a×(T CH4 +R CnHm )-b×T CO2 , in which, T H2 represents the measured volume concentration of H 2 using TCD, T CH4 and T CO2 represent the volume concentrations of CH 4 and CO 2 measured using NDIR, respectively, a is 0.13989 and b is -0.11026 and R CnHm is the revised volume concentration obtained in step 2); and 4) calculating the calorific value of the coal gas (Q) using the equation Q =T CO × 12.64+ R H2 × 18.79 + T CH4 ×35.88 + R CnHm ×93.18, in which, T CO and T CH4 represent the measured volume concentrations and R H2 and R CnHm represent the revised volume concentrations. - measuring a volume concentration of H 2 (T H2 ) in the coal gas by using a thermal conductivity detector (TCD), - measuring a volume concentration of O 2 in the coal gas using an electrochemical detector (ECD), and - calculating the calorific value of the coal gas via measured and revised volume concentrations of various gases; 1) measuring volume concentrations of CO, CO 2 , CH 4 , and C n H m in the coal gas, represented by T CO , T CO2 , T CH4 , and T CnHm , respectively, in the coal gas using non-dispersive infrared (NDIR) technology; 2) calculating a revised volume concentration of C n H m (R CnHm ) using the equation R CnHm = T CnHm -A×T CH4 , in which T CnHm and T CH4 represent the volume concentrations of C n H m and CH 4 measured with NDIR, respectively, and A is 0.02868; 3) calculating a revised volume concentration of H 2 (R H2 ) using the equation R H2 = T H2 -a×(T CH4 +R CnHm )-b×T CO2 , in which, T H2 represents the measured volume concentration of H 2 using TCD, T CH4 and T CO2 represent the volume concentrations of CH 4 and CO 2 measured using NDIR, respectively, a is 0.13989 and b is -0.11026 and R CnHm is the revised volume concentration obtained in step 2); and 4) calculating the calorific value of the coal gas (Q) using the equation Q =T CO × 12.64+ R H2 × 18.79 + T CH4 ×35.88 + R CnHm ×93.18, in which, T CO and T CH4 represent the measured volume concentrations and R H2 and R CnHm represent the revised volume concentrations. <EOS>