Abstract: The time effect of friction of bakelite, oil nylon and TS 70 slideways is studied. The result of prototype test of bakelite and TS 70 slideways is summarized with an industrial example. The time effect of friction of slideway is explained with adhesion theory of friction. It has been suggested that the larger creep deformation of viscoelastic slideway materials causes the extension in the real contact area of the slideway pairs, thus a stronger friction time effect is observed. The enhanced friction time effect of viscoelastic slideway materials is also dependent on the stronger shearing modulus time effect which increases the interfacial shearing strength.