As bridges age, structural weakening due to heavy traffic and aggressive environmental factors becomes more important. These factors lead to an increase in repair frequency and decrease in load carrying capacity. Structural weakening can decrease the lifetime period and prevent the serviceability of bridges. In order to avoid the disadvantages of deterioration, the lifetime performance prediction of a bridge system should be correctly predicted. Using the lifetime performance prediction, the remaining service life of the bridge system could be predicted. In addition, the best maintenance and repair strategies kept the system in safe can be obtained. In this study, a regression model is investigated as performance prediction model. Moreover, effects of the changes of the coefficients of regression model on the performance curve are examined