Abstract: The manganese bath method is one of the most widespread and exact method to measure neutron source emission rate (neutron source intensity) absolutely at present. Pouring some ⁵⁶Mn solution with known activity into the bath, the system efficiency can be obtained from γ counts of ⁵⁶Mn, which is measured by two NaI(Tl) detectors. From saturated counts of a ²⁴¹Am-Be(α, n) neutron source in the bath, the source emission rate can be obtained. An standard ²⁴¹Am-Be(α, n) source which is the transfer source of the CCRI(Ⅲ)-K9.AmBe international key comparison organized by the Comité Consultatif des Rayonnements Ionisants, was measured absolutely with the neutron source emission rate standard equipment (manganese bath method). The result is coincident with the average value of the comparison within the uncertainties, therefore the reliability of the standard equipment is verified.