In this article, sliding mode control (SMC) is applied to the Couple-Tank system, which is the typical application of the fluid level tank system used in industrial facilities and its control is examined. The mathematical model of the nonlinear Couple-Tank system was found out for both tank systems. The system was designed by combining the dynamic equations of the Couple-Tank system with the sliding mode control. The important aspect of SMC is to control a nonlinear dynamic system that is exposure to external disturbances or uncertainties using a switching function that ensures that the system states remain on the slip surface. The sliding mode control (SMC) was chosen by the author because of its robustness against parameter changes and distortions. In this article, the second order SMC technique is used to avoid the unwanted chattering effect. The control signal for the sliding mode control was calculated as the sum of the switching control signal and the equivalent control signal. The transfer function of the nonlinear Couple-Tank system was calculated by the Taylor series linearization method. In this article, the Tank 2 transfer function was determined by the ratio of the input voltage of the system to the fluid level. The sliding mode control applied to the Couple-Tank system and the feed forward PI controller (FF-PI), which is another type of control, are compared. The monitoring of the measured fluid level to the reference fluid level and error detection between the measured liquid level and the desired fluid level were examined in the simulation environment of the Couple-Tank system designed by applying the sliding mode control (SMC). It has been observed that the system designed with sliding mode control (SMC) can follow the desired fluid level quite successfully.