The invention discloses a controllable isotopic neutron source. The controllable isotopic neutron source comprises a sealed container; a substrate which is arranged in the sealed container and is usedfor plating an alpha particle emitter, wherein an alpha particle emitter plating layer is arranged at a part zone on the periphery of the substrate; a metal target nucleus arranged in the sealed container, wherein the metal target nucleus is arranged around the substrate with a certain distance from the periphery of the substrate; the substrate and/or the metal target nucleus are designed to be capable of rotating around an axis, so that the relative positions of the alpha particle emitter plating layer on the substrate and the metal target nucleus is changed, and neutron sources of differentintensities are obtained; and neutron beam pulse of different frequency is obtained through changing the rotating speed of the substrate. The controllable isotopic neutron source is capable of realizing neutron source adjusting, obtaining neutron beam pulse of different frequency, realizing neutron emission switch control, improving neutron source safety, is simple in structure, small in size, and light in weight.