The utility model discloses a stifled alarm is prevented to chromatograph, stifled alarm is prevented to chromatograph install on the sample gas pipeline, and it advances interface, audible and visual alarm, control switch and sample gas pump power switch including casing, self -lock device, negative pressure table, compressed air, the negative pressure is shown to connect on the inside sample gas pipeline of casing, and it is equipped with upper limit contact and lower limit contact, and the lower limit contact is normally closed state, and after it reaches the disconnection of lower limit pressure value, self -lock device will control audible and visual alarm and report to the police, and upper limit contact is open state, and after it reaches upper limit pressure value closure, self -lock device will control sample gas pump power switch and close to the control sample gas advances the interface and compressed air advances the interface intercommunication, the utility model discloses a negative pressure of negative pressure table monitoring sample gas pipeline changes, adds circuit such as monitoring, warning, reaches the purpose that the warning operator on duty is in time handled, is protected accurate valuable instrument and improves work efficiency, reduces the construction that causes because of the equipment problem and pauses, improves the prescription of whole exploration operation.