The gray time-varying parameters model of unequal interval is built to avoid the faults of classical gray model, following the information handling principle of the gray theory and leading a forgetting factor into the model to correct the prediction results. In the model, both time-varying property and the correcting effect of the forgetting factor are considered, so the prediction error is smaller. The case study shows that the error of finishing settlement can be controlled within 23% by the Gray TVP Model. As a result, the error checking indicates the precision grade is updated after prediction results is corrected by the forgetting factor.