A dustproof element is mainly applied to a ball screw. The ball screw comprises a threaded rod and a nut arranged on the threaded rod in a sleeving manner; the dustproof element comprises an annular body and an elastic valve block; the annular body is arranged at one end of the nut, and the threaded rod penetrates the annular body; an abrasive dust outlet is formed in the outer annular face of the annular body, and one end of the abrasive dust outlet communicates with a spiral passageway formed between the threaded rod and the nut; the elastic valve block is arranged at the other end of the abrasive dust outlet of the annular body; and in this way, when fluid applies thrust on the elastic valve block, the elastic valve block can be pushed away so that the abrasive dust outlet can be in an opened shape, at the moment, abrasive dust can be smoothly discharged from the abrasive dust outlet along with the fluid, and the effect of prolonging the service life can be achieved.