Gamma-ray burst (GRB) is one of the most explosive phenomena in the universe, the mass dominated dynamics of both forward and reverse shock evolution process is already well studied. Observations indicate that the jet from GRB may be magnetized, and the dynamics of the forward-reverse shocks produced by interactions between the jet and the interstellar medium will have new features once the jet was magnetized. Zhang & Kobayashi had derived a analytic solution of the dynamics based on the ideal MHD condition. This article derives a set of general dynamics equations with some related numerical calculations.
