There are some particles attached to the side of dipolar chains in magnetorheological fluids. The reorganization and rupture of these chains are simulated when a tension and shear movement are applied, respectively. And the micromechanical behavior of these chains is also analyzed. It is found that the attached particles move into the chains during the tension, which increases the strain when the chain ruptures. While in shear process, attached particles introduce localized weakness in chain, which makes the chain rupture more easily and decreases the strength of the chain.