In this research, the positioning control of a water hydraulic servo cylinder system with the simple adaptive control (SAC) is discussed. Conventional model reference adaptive control (MRAC) also achieves good tracking performance for cylinder control, but the controller structure is much more complicated and has less robustness for disturbance in real application. Compared with MRAC, SAC has simpler and lower order structure, i.e. higher feasibility. However, no result has been reported on SAC application for water hydraulics. In this paper, we examined and evaluated the control performance of SAC on a water hydraulic servo cylinder system, and it was confirmed that SAC gives 1) better tracking performance compared with PI control, and 2) comparable control precision and higher robustness compared with MRAC.