In this study, an online-tuning method for derivative order term of Fractional PD and Filtered Fractional PI controllers is presented. For this purpose, closed-loop step response is divided to certain regions and a different tuning strategy is proposed for each region. These tuning strategies basically depend on the error between the system output and reference input. The strategy formulas are formed as linear equations arranged in terms of system error and system time constant. Simulations are performed to show the effectiveness of the proposed on-line tuning method on various systems.