Based on the data obtained from tank testing the resistance performance of a trimaran planing hull is explored. The variation rule of resistance performance in different displacement and longitudinal position of center of gravity is studied. The effect of stern trim tab on resistance performance of a trimaran planing hull is tested. The experimental results of the trimaran planing hull are compared with a monohull. Experimental results show that the trimaran planing hull has a great capacity for load. The type of sponson and channel type extensively affects resistance performance and longitudinal stability. The trimaran planing hull's resistance is higher than the monohull planning hull on a condition of Fr ▽ < 3.0. Moving toward transom of the center of gravity and the installation of stern trim tab are propitious to decrease resistance, and the influence of the movement of the center of gravity position is smaller compared to the monohull.