Abstract: A production method for civil mixed fuel gas with light hydrocarbons mixed with air and coal gas, which is characterized in that the preparation method of the said civil mixed fuel gas is as follows: a. filtering liquid light hydrocarbons, and pressuring; b. heating and gasifying the light hydrocarbons in the heating gasifier; c. mixing gasified hydrocarbons with air or pressured air in a mixing chamber to form a mixture of light hydrocarbons and air; d. storing the mixture in a middle gas-storing tank after measured by oxygen meter; e. mixing coal gas and light hydrocarbons mixed with air in a gas-mixing chamber to form mixed fuel gas; f. storing the mixed fuel gas in a gas-storing tank after measured by oxygen meter; g. transmitting and distributing the mixed fuel gas to user terminal in a low or middle and low pressure two grade form. The present invention makes use of the liquid hydrocarbons with boiling range below 80 deg. C.