Z-pinch is the system with a rather small confinement time. For this reason it is necessary to create in it a plasma of high density in order to get the (n tau,T) parameters required for the Inertial Confinement Fusion. Shown, that it is more easy to get the required plasma parameters for the thermonuclear fusion in conditions of the radiative collapse, than in conditions of the adiabatic compression. Influence of the initial conditions on the radiative collapse is also discussed.