China Low Activation Martensitic (CLAM) steel has been selected as the primary candidate structural material for Chinese Helium Cooled Ceramic Breeder ITER Test Blanket Module. In the present work, the hydrogen transport behavior in CLAM steel have been experimentally measured with gas evolution permeation technique in the temperature range of 573–823 K at hydrogen pressures of 10²–10⁴ Pa. The pressure exponent n of permeation was between 0.54 and 0.55 and it showed that the permeation was approximately pure diffusion limited. The hydrogen transport parameters of CLAM were presented based on experimental results at 10⁴ Pa, and the transport parameters were Φ(mol·m⁻¹·Pa^−1/2·s⁻¹) = 3.11 × 10⁻⁸exp(-38712/RT), D(m²·s⁻¹) = 1.19 × 10⁻⁷exp(-16404/RT), Ks(mol·m⁻³·Pa^−1/2) = 0.27exp(-22308/RT). All those transport parameters were compared with the available data corresponding to several other RAFM steels and the results shown the similar hydrogen transport behavior of the RAFMs.