Abstract: Although the proteasome pathway has long been considered one of the most important proteolytic systems in pollen development, the dynamic changes of proteasome activity and distribution during pollen development are largely unknown. We performed fluorogenic kinetic assays using fluorogenic substrate sLLVY-AMC to measure proteasome activity in Pinus bungeana pollen grains. Our experiment results revealed that proteasome activity increased from the uninucleate to 3-cell stage, but slightly decreased in mature pollen grains. Immunofluorescence labelling detected proteasome signals in the nuclei of pollen grains at all stages as well as in cytosol. Unequal distribution of proteasomes was observed in the two degradating prothallial cells. Our data indicate a link between pollen development and dynamic changes in activity and distribution of proteasome, and proteasome might take a part in the degradation of prothallial cells.