Maneuverability is crucial to the safety of trimaran. However, investigations on the maneuverability of high-speed trimaran are still limited, especially by water-jet self-propulsion model test. In this paper, a trimaran model powered by water-jet impetus is developed, and a water-jet self-propulsion model test is carried out in open calm water. Firstly, direct navigation test is carried out to measure the relation between the rotation speed of the water-jet thrusters and the advance speed of the trimaran model. Then, maneuver tests of the trimaran model with three layouts are carried out at different initial advance speeds and two nozzle angles of water-jet thrusters. The maneuverability parameters of the trimaran with various layouts and nozzle angels at different speeds are measured, such as moving trajectory, moving velocity, heading angle, hull attitude, turning diameter, overswing angel, period and so on. Based on the experimental results, the influences of the lateral and the longitudinal position of the side hulls on the maneuverability of trimaranare discussed and analyzed.