It is necessary to monitor plutonium aerosol when doing experimental research with plutonium material. Plutonium material experiments are usually carried out in sealed containers, which guarantees that the plutonium aerosol will not leak out to the environment. The widely-used monitoring equipment are not suitable for plutonium aerosol monitoring in sealed containers because of its large volume. A new plutonium aerosol measurement system based on wavelength shift fiber and silicon photomultiplier (SiPM) is developed. In the new plutonium aerosol measurement system, ZnS(Ag) scintillator is used as detection material and wavelength shift fiber is used as photon transmission media . The new plutonium aerosol measurement system has the advantages of customizable detector size and shape, low power consumption, and relatively simple structure, which realizes remote measurement of plutonium aerosol in sealed containers. The measurement system can also discriminate α particles in n/γ-mixed radiation field.