Abstract: The boiling heat transfer on packed bed with 8 mm carbon steel balls was investigated. The boiling curves were obtained at the increasing and decreasing conditions of heat flux, which made it possible to detect the boiling hysteresis phenomena. The various factors which impact on the boiling hysteresis in the channels, such as the axial and radial positions in the test section, the superficial flow velocity etc., were investigated. The experimental results show that the nucleation hysteresis is weak at high liquid velocity, far from the outlet and near wall situations. When liquid superficial velocity and surface roughness of the fillers increase, the degree of annihilation hysteresis of boiling increases.