This paper deals with the damping characterstics of short carbon fiber、SiC whisker and 2B₂0₃.Al₂O₃ whisker reinforced magnesiurm composites，analyses their mechanical properties and fracture surfaces. Damping behavior of magnesium composites vary as reinforcers. C(f)/Mg composites exhibit higher damping than whiskers rein-forced magnesium composites. Fiber/matrix interface plays an important role in damping.