Abstract: For neutron energy ranging from thermal to 20 MeV, kerma coefficients of elements H, C, N, O, Ar, dry air, and the ICRU 4-element tissue, were deduced from lately updated microscopic cross sections (ENDF/B-Ⅶ). On the base of these kerma coefficients and Monte-Carlo simulation using the MCNP code, ambient dose equivalent for unit neutron fluence of Am-Be source was calculated as 373.0 pSv•am². Besides, based on the neutron spectrum of a Chinese-made Am-Be source calculated by our group, the ambient dose equivalent was calculated as 374.0 pSv•cm². Neutron and γ-ray absorbed dose rate in the air at 1 m distance from the source were calculated with the results of 1.457×10^－2 and 1.580×10^-1 μGy/(GBq•h), respectively.