Hydraulic and pneumatic control play an important role in mechatronic systems. Selection of control devices in designing mechatronic systems that uses hydraulic or pneumatic circuits studied by many researchers. A description of both hydraulic and pneumatic theory is introduces comparing between hydraulic and pneumatic systems based on their applications, used fluid, advantages and disadvantages and functions. Also, comparison between different power systems showing the difference between them in power source, cost, uses, affected parameters and advantages and disadvantages is studied. the importance of using hydraulic and pneumatic systems in different fields of industry is introduced.