Abstract: The feasibility of observing deep scattering layer(DSL) by acoustic correlation current profiler(ACCP) is discussed in this paper.ACCP can estimate the three-dimension velocities of the currents.The projector of ACCP transmits code-modulated pulse vertically and several hydrophones receive backscattering signal.Two methods are presented to observe DSL respectively based on backscattering strength and vertical velocity.These two methods are used to observe DSL with the sea trial data of 23 kHz prototype ACCP.The results of the observation indicate that ACCP can observe the distribution and migration of DSL intuitively.