Abstract: Chemical mechanical polishing (CMP) is one of the mosteffective technologies in modern ultra-precision processing. In this paper,firstly, we deduce the model of CMP with convection effects, and researchthe pressure distribution by changing different parameters. Then, weconsider the model of CMP under the magnetic fluid slurry and externalmagnetic field, and research the pressure distribution in the externalmagnetic field. The numerical results show that pressure distribution of themodel with convection is more consistent with the known empirical results,and more efficiently explain the sub-ambient pressure in the CMP. Theresults also show that we can efficiently change the distribution ofpressure by external magnetic field, so these technologies can provide a newreferenced way for the wafer's global planarization.