The invention discloses a gas detection linkage air fan start system for a rig machine. The gas detection linkage air fan start system comprises a gas detection system and a rig machine ventilation air fan start system, the gas detection system and the ventilation air fan start system are combined together by receiving no source dry contact signals, by means of the arrangement of a three-positionself-locking switch control system, an existing rig machine manual ventilation air fan start system is simultaneously improved into the gas detection linkage air fan start system for the rig machine with the mode selection function and the zone control capability. By means of the gas detection linkage air fan start system for the rig machine, the ventilation air fan start mode selection function of rig machine enclosed areas can be realized, and the gas detection linkage air fan start function with the zone control capability of the rig machine enclosed areas can be realized, and then the function reliability of a present enclosed type rig machine with forced ventilation, the function reliability of the ventilation air fan start system arranged on the present enclosed type rig machine withthe forced ventilation and the operation safety of operators can be effectively guaranteed, and the automation level of the enclosed type rig machine with the forced ventilation and the ventilation air fan start system of the enclosed type rig machine with the forced ventilation is effectively improved.