Abstract: A method adopting the charge analog digital conversion technique to calibrate a current scintillation detector is described. Each pulse charge produced by a single particle is collected and recorded. Calculating the mean current, the sensitivity of the detector is measured. The results agree with the measurement presented by the traditional direct current method within ±8%. This new method can get higher accuracy, subtract background easily and it does not depend on the intensity of the radiation source. By applying time-of-flight method, it is capable of particle discrimination. It can separate the pulse charge produced by neutron from that produced by gamma in a neutron-gamma mixed field. The sensitivity of current detector to each type of particle can be measured separately. This metho