We put forward, in the essay, the assumption of the magnetic model of accretion disk with magnetic viscosity. Optically thick, is the disk whose radiation is thermal in the outer region, while in the inner region it is optically thin and the radiation mechanism is synchrotron. From this we derive the general dispersion relation of the accretion disk for the radial oscillation and discuss the stability and overstability in each region of the disk. The conclusion, therefore, is reached that the accretion disk is globally stable and locally overstable. The global stability may avoid the break of ...
