Vortex shedding from a circular cylinder is simulated by means of the discrete vortex method. The shear layer emanating from the separation point is approximated as a sheet vortex which is in turn represented by a sequence of discrete vortices. The strength of these vortices is calculated from the vorticity shedding rate and introduced at a small distance off the side ($Theta=pmpi/2$) of the cylinder surface in regular time step. Sheet vortex cutting, rediscretization and replacement of vortex by vortex segment are put to use to enhance stability of the sheet vortex evolution. The simulated vortex distribution pattern very well reproduces structure like the Karman vortex street. However, as for the force coefficients, the qualitative properties are correctly predicted but some more improvements are needed for the quantitative accuracy.