Underwater gliders are used for deep-water gliding to observe large areas with minimal energy consumption. The pitch angle of the underwater glider is an important control parameter. This study involved designing a fuzzy-PID controller for the pitch angle of an underwater glider based on hydrodynamics analysis. The formula of pitch angle is obtained and a system identification method was used to identify the transfer function based on the time-domain equation and initial experimental data. The fuzzy-PID control algorithm was used to design the controller. Lake and sea trials indicated that the minimum overshoot reached 0% and the settling time was about 34s when the change of the angle was 15 degrees. The minimum steady-state error was 0.8 degrees. These advantages could reduce the consumption of energy and improve the accuracy of gliding trajectory. Therefore, this control algorithm should be applied to control the pitch of the gliders. (C) 2017 All rights reserved.