The vibration of fire smoke exhausting robot affects a lot on running quality. The rotational speed of engine is fixed and the vibration of the robot’s engine has a certain dominant frequency, so a dynamic vibration absorber is possible to reduce the vibration. In this paper a typical structure has been designed, and the linear relationship between dominant frequency and engine speed has been surveyed. The elongation of the spring has been deduced to the only key parameter due to the linear relationship and determined speed. An evaluation standard of damping effect was set up, the maximum acceleration value and root mean square value of acceleration and relative value of acceleration were taken as the evaluation indexes. Comparison tests were made, the damping effect was taken into account. The experimental results demonstrate the practicability and effectiveness of the new simplified absorber.