  We analyse the CP asymmetry of the B -> phi K_S process in general
supersymmetric models. In the framework of the mass insertion approximation, we
derive model independent limits for the mixing CP asymmetry. We show that
chromomagnetic type of operator may play an important role in accounting for
the deviation of the mixing CP asymmetry between B -> phi K_S and B -> J/psi
K_S processes observed by Belle and BaBar experiments. A possible correlation
between the direct and mixing CP asymmetry is also discussed. Finally, we apply
our result in minimal supergravity model and supersymmetric models with
non-universal soft terms.
