By means of particle tracking autoradiography (PTA), the diffusion coefficients of B between 900 - 1200 o C were measured in 04MnNbB steel, 25MnTiB steel, Ni-B, Fe-30% Ni-B and Fe-3% Si-B alloys, and the frequency factor D 0 and activation energy Q were obtained respectively. The experimental results indicate that there was an obvious difference between the present result and that obtained by Busby (in 1953). It was found that the B diffusivity in γ-Fe increased as Ni added. The diffusivity of B in Fe-3% Si-B alloy with bcc structure was much slower than one obtained by Busby in α-Fe (1954), however which was much rapid than the results obtained in γ-Fe (with fcc structure).