The low-frequency internal friction in Cr75Fe16Mn9 alloy has been measured in temperature range of 100—600K and at frequencies lower that 10Hz. It is found that an internal fraction peak at 450K and corresponding jump of modules exist in the paramagnetic phase. This indicates there is a disorder-order transition on coupling states between individual spins for the Cr and Fe components. There is a broad internal friction peak in the temperature range from 200 to 300K, which consists of a peak at 280K and the extended broad peak at 220—270K. We suggest that this effect is the reflection of the spin density wave antiferromagnetic transition and the coexistence of different magnetic phases in the alloy. Our results reflect the fact that internal friction method would be a sensitive and effective probe for investigating the change of microstructure including electric structure.