<p>The CIAE manganese bath facility has been employed to measure the emission rate of a radionuclide neutron source in 5 × 10⁵s⁻¹ ~ 1 × 10⁹s⁻¹ for nearly forty years. In order to measure neutron sources with lower emission rate, a reduced-volume manganese bath facility was developed. By reducing the bath radius to increasing the specific activity of the solution, the emission rate of neutron sources which is nearly an order of magnitude lower than the previous manganese bath can be measured by the reduced-volume manganese bath system. Two neutron sources with lower emission rates which were 4.09 × 10⁴ s⁻¹ and 1.75 × 10⁵ s⁻¹ with an uncertainties of &lt; 1.5% (<i>k</i> = 1) have been measured with the new bath.</p>