Abstract: The physical equations of direct-drive cylindrical hydrodynamic instability in the LARED-S code, the geometry for the direct-drive cylindrical targets, the slide grids and some related techniques in the simulation are given in the paper. In the simulation of direct-drive cylindrical implosion experiments at OMEGA laser facility, the physical model of the target is simplified. The ablator, the marker layer and the interior foam of the target are taken as ideal gases, with different densities and the completely ionized charge state and single-temperature approximation are supposed during the implosion. The effect of classical electron thermal conduction is included while other factors such as radiation transport and nonlocal electron transport are neglected in the calculations. Simulation re