The invention discloses an intelligent monitoring method and system for tunnel gas. The method comprises steps as follows: receiving gas concentration signals transmitted by multiple gas sensors in real time; acquiring tunnel space information; fitting gas concentration distribution in the tunnel range according to the space distribution information and concentration of the gas sensors; calculating a maximum value point of the gas concentration distribution, and generating warning information according to position information of the maximum value point and concentration information and sendingthe warning information to a user terminal if the maximum value point is larger than a first set threshold value and smaller than a second set threshold value; formulating an escape strategy while the warning information is generated according to the position information of the maximum value point and the concentration information and sent to the user terminal if the maximum value point is largerthan the second set threshold value, and generating alarm information on the basis of the escape strategy and sending the alarm information to multiple alarms. According to the intelligent monitoringmethod and system for the tunnel gas, real-time portable monitoring of the tunnel gas concentration can be realized, and effective warning and behavior guidance are provided for people in the tunnelwhen the gas concentration exceeds the standard.