The utility model provides a sensor fixer, includes with sensor draw-in groove complex mount, is used for to fasten the mount tightly decides the screw, be provided with the hold-down mechanism who is used for the jam sensor lead wire on the mount, be provided with on the mount and tightly decide screw complex screw hole. Has following advantage: 1. Stationary sensor that can be fine makes it no longer drop, 2. Testing personnel need not divert one's attention to pay close attention to the sensor again and whether come off, can be used in whole energy to test and judge and test analytically to work efficiency has been improved, 3. Improve the utilization ratio of sensor, avoided unnecessary economic loss, 4. Make the sensor with good by gas testing room contact, improved experimental accuracy.