Abstarct: Many industrial and scientific processes require knowledge of the quantity of content o tanks and other containers.for example in steam power plant there are many of tank and control with several control operation the same as viscosity,temperature and liquid level.since liquid level control is very importantin successful, efficient idea to cause output quality improvement and economic enjoyment . Adaptive control represents a special type of control with nonlinear feedback in which the states of the process could be divided into two categories: parameters which change slowly and state variables which change faster. Many processes are characterized by the fact that their parameters are variable or unknown, which demands adaptive systems for their control. Adaptive control systems are nonlinear even if the system under control represents a linear system or a system which could be described by a linearized mathematical model. The structure of adaptive systems and the mechanisms used for the adaptation of unknown or variable parameters impose the nonlinearity of the control system. The thesis considers several types of adaptive control systems (gradient approach - MIT rule for parameter adaptation, reference model adaptive and self-tuning regulators) and their application to level control. Known hydraulic level-systems are now considered from a different point of view. Standard hydraulic level control systems provided keeping the level of a liquid in a reservoir at desired constant value. That could be achieved by linear feedback gain control system. If the aim of control is to make the level of a liquid in a reservoir change according to a specified function, then the adaptive control system is needed, because the parameters of the system under control are variable due to variable liquid level. The case when the system parameters are unknown is also considered.the effectiveness of the proposed method is illustrated via a comparison between that techinqe and PID method