In this study present comparison of PID and FUZZY controller in the cascade tank system. In order to control cascade tank system, fuzzy and pid controller was simulated in Matlab /Simulink. The system has two tanks. The water level in the tanks and the stream provided by pump are the system parameters. The current which is applied to the motor is the only control variable in the system. In this system fuzzy controller are compared with pid controller. The signals of the system's output are observed in matlab.