Abstract: Under multiple gas sources environment, the quality of natural gas and substituted natural gas is quite complex. In order to ensure the safety of long distance pipeline and the natural gas metering accuracy, the gas quality of conventional, unconventional natural gas and substituted natural gas is discussed. The gas quality control demanded in multiple gas sources environment is summarized. In order to formulate the national standard of quality requirements for all kinds of gas entering long-distance transmission pipe networks, the control limits were discussed to find out the limits which including the concentration of total sulfur, hydrogen sulfide, carbon dioxide, carbon monoxide, hydrogen, oxygen, particles, and water content/water dew point. These parameters are fully discussed.