The isochronous theory is popular in modelling the time-dependant strength and deformation characteristics of polymer geotextile for the design of reinforced soil structures. According to this theory, the tensile load of reinforcement is a function of instantaneous strain and elapsed time. Thus, the design strength would reduce monotonously with time elapsing. It is shown that the isochronous concept is not able to explain the tensile behavior of reinforcement observed in the present study, in particular the behavior after loading is restarted at a constant strain rate after a creep and relaxation. Experimentally observed time dependency of tensile characteristics of geogrid is reported, and an analytical simulation of the tension test results on geogrid by one type of three-component model was performed. The results of an experimental and analytical investigation showed that the proposed constitutive model is relevant to simulate the time-dependent deformation and strength characteristics of the tested geogrid.