The paper concerns the influence of time and strain-rate effects on the clays in one-dimensional consolidation under constant effective stress. An improved creep constitutive model is deduced, by analyzing the stress-strain theory developed by yin and sekiguchi. Treating the sample as a single system and applying the boundary conditions at the system level, differential mathematical equations to the consolidation problem of clays are obtained. The proposed differential mathematical equations have advantages in their ability to (i) not clarify the primary consolidation and secondary consolidation deformation. The error in calculating consolidation deformation which is caused by the argument about end of primary consolidation can be avoided. (ii) obtain the model parameters easily. How to achieve parameters by experiment is described in detail in the paper. (iii) be programmed and solved readily for the finite difference description of the problem. Results from clays have been used to examine the validity of the model. It is shown that the proposed model can describe the consolidation of clays well.