The experimental results of measuring the critical heat flux of Helium-I under natural circulation and forced flow are described in this paper. The direction of the experiments under natural circulation depends upon the real geometry of superconducting magnet cooling channels. The influence of the nonheated zones and local hydraulic resistances on the critical heat flux is discussed and some experimental results are given. The critical heat flux of saturated Helium-I under forced flow in vertical tube is measured in a wide range of pressure, quality, and mass velocities. The expressions have been obtained which describe the dependency of the critical heat flux upon the different conditions.