Abstract: The uniaxial ratcheting of short glass fiber reinforced polyester resin matrix composites was studied experimentally at room temperature. The ratcheting behaviors of the composites were discussed under different conditions. It is shown that the ratcheting behavior of the composites is similar to that of the un-reinforced matrix in macro-scale，namely，the ratcheting also occurs in the composites under asymmetrical stress cycling，and the ratcheting strain increases as the stress amplitude and mean stress increase；the ratcheting has great time-dependence，i.e.，the ratcheting strain depends on the stress rate and peak stress hold time. It is concluded that the viscous deformation of the matrix should be involved in constructing a constitutive model for the ratcheting of the composites.